Build-a-Keep^

Base/Home Building^

The Construction costs and times below assume you are building in a town that contains a Mythallar. If you wish to instead build in the wilds, cut the construction time in half and double the cost. However once your walls are complete, a time stablising mythallar will be placed in the structure, so any future constructions will have the same cost and construction time as those in towns. (mythallars can not be moved once they are activated.)

The construction costs includes materials, labor and land. The player need not be present during construction. However if the character is present and contributes to labor for the entire duration, you may remove a quarter of the cost. Multiple character may work on a structure in this way to benefit multiple times (a quarter off the remaining, not off the total).

Finally the hirelings displayed on each room entry are the number that must be employed full time at the building, and thus represent upkeep costs of the structure. After 7 days of not recieving payment hirelings will quit their job and the structure will cease providing its benefit. Hirelings that are given lodgings in your structure only require half payment.

To build you must lay Defensive Walls.
For every time you build Defensive Walls the size of your base increases.
Be aware you do NOT have to build a moat, but if you do build a moat, you must build it once for every wall you have, and must continue to build it as you expand.

Defensive Walls

Construction Cost: 1,250 gp
Construction Time: 15 days
Benefit: Grants 2 Build Points, ALSO they provides a 5-foot thick, 20-foot high wall that encircles the structure, made of wood, stone, or magical force, within 30 feet of the edge of the structures physical building. Contains gates and small towers for sentries. Each five-foot wide, five-foot thick panel of this wall has an AC of 15 and 800 hit points. This may be built multiple times.

Moat

Construction Cost: 625 gp
Construction Time: 7 days
Requirement: Must build 1 moat for every walls you have, each time a new wall is built, a new moat must also be constructed.
Benefit: Provides your structure with a rougly circular moat around it, which is 200 feet wide and 10 feet deep, the inner side of which is within 40 feet of the edge of the structure’s physical building. Creatures not large enough to touch the bottom in this moat must swim through it, while creatures large enough to walk on the bottom while remaining somewhat above water treat the moat as difficult terrain. The moat also has a drawbridge, 20 feet wide and long enough to span the moat, that can be raised and lowered from a gate inside your structure.

Building List

The times and costs listed here assume a mythallar has already been constructed. The Min hirelings are the amount you MUST have employed in that building else it will become unusable. The Max hirelings is how many you must hire to get the max benefit from the room, though you may choose to hire more than that. “U” = Unskilled and “S” = Skilled.

Buildings

Alchemist’s Lab

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: All transmutation spells cast by the owners of this structure and their allies while they are within this room have twice their normal duration, and half their normal material cost. In addition, alchemists supplies are always considered to be present here, and any checks made with these tools are made with advantage by individuals who have profiency with them. Additionally this room counts as having an additional person for the purposes of crafting things that require an alchemy kit.

Animal Pen

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: This room allows creatures to be held securely and safely, whether or not they desire to be, until you choose to release them. The creatures must not be humanoid, and this room may hold five creatures sized small, three sized medium, or one sized large. This room also may be bought and constructed multiple times, and allowing for a single sized larger creature. eg 2 rooms points will allow for 10 small, or 6 medium, or 2 large, or a single huge creature. This room does not automatically include creates, they must be acquired through other means.

Arcanist’s Study

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: Choose a school of magic. While present within this room, spells in the chosen school cast by the owner and their allies have twice their normal duration, and half their normal materials cost. Intelligence (arcana) checks made here that deal with this chosen school of magic have advantage, this includes the arcana check made for spell merging. This room may be built multiple times, each time a different school must be chosen. Additionally a person performing the Spell Merging downtime activity only has to pay 50 gp instead of 100 for the initial fee.

Armory

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: When the structure is under attack, any hireling that is not a spellcaster or soldier may visit the armory and afterwards count as a guard (Monster manual, page 347). Hirelings equipped in this way may also be used offensively rather than simply in defense of the structure. Doing so deprives a structure of its hireling staff however, and removing more than a quarter of your structure’s hirelings from its grounds will cause any other benefits the structure provides to cease, as the hirelings left behind struggle to cover for those absent.

Bank

Size Cost: 2 room points
Construction Cost: 1,250 gp
Construction Time: 15 Days
Benefit: This room contains four 30-foot by 40-foot vaults, each with a 20-foot tall ceiling. The owner of this structure and their allies may stash any amount of gold or reasonably-sized treasure in one of the vaults, which requires a key to access (one key comes standard with each vault). Unguarded vaults may be broken into with thieves’ tools by making five successful DC 15 Dexterity checks within an hour. The Vault doors are three-foot thick, 5-foot radius circle of steel by default, with an AC of 19 and 25 hit points. When you first build this room, or as a room modification at a later time, you may expend an additional 2,500 gp and 15 days of effort to build mithral doors (AC of 21, 50 hit points) for the vaults, or you may expend an additional 5,000 go and 30 days of effort to build the vaults with adamantine doors (AC of 23, 100 hit points). In addition, if this room is staffed with at least 10 skilled hirelings trained in either Insight or Investigation, the room generates an income equal to 5% of the total currency stored there, every 30 days.

Baths

Size Cost: 1 room point
Construction Cost: 675 gp
Construction Time: 7 days
Benefit: While taking a short rest within this room, the owner of this structure and their allies double the hit points they regain from using hit dice (including those granted by consitution modifiers). Additionally, taking a short rest within this room grants a number of temporary hit points equal to the structure’s total possible room points. These temporary hit points last until they are lost, or until the next long rest.

Battle Ring

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 15 days
Benefit: Those who spend at least an hour sparring or training here gain advantage on initiative rolls and on the first attack them make in each combat, till their next long rest. Additionally those who are training in a new weapon, armor or shield profiency may halve the required learning time (after applying modifer).

Boutique

Size cost: 1 room point
Construction Cost: 675 gp
Construction Time: 7 days
Benefit: When you first build this room, choose one merchant from the merchants table in the Traders and Merchants section. This merchant is in permanent residence at your structure, though the quality of their goods changes every 7 days. If the merchant’s goods are of a quality less than medium, you may reroll any number of times until you receive a result of medium or greater quality.
You may change the merchant in residence here at a later time by paying 300 gp to renovate the boutique. This process leaves the boutique unavailable for 15 days, after which a new merchant is selected, as they were when this room was first created. If your structure is located in an area that can reasonable expect trade, this room generates an income of 30 gp x 3d4 every 30 days. This room may be built multiple times.

Caravansary

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: Roll four times on the merchants table at the end of this sections. These merchants are present for 7 days, after which they depart and four new randomly-rolled merchants arrive, continuing this pattern every 7 days. This room generates an income of 20 gp x 2d10 every 30 days.

Catacombs

Size Cost: 1 room point
Construction Cost: 675 gp
Construction time: 15 days
Benefit: Dead bodies may be interred here, and suffer no degradation for the purposes of necromancy spells. Whne this room is first built, it comes with five skeletal servants, each one counting as an unpaid, unskilled hireling for any structure or room requirements. These servants have an AC of 10, 1 hit point, and a Strength of 8, and cannot speak or attack (unless equipped by the armory and doing so in defense of your structure). The servants do as commanded by the owner of the structure and their allies, and stand motionless in place if commands conflict, waiting until new commands are given. These skeletal servants can perform simples tasks that a human servant could do, such as fetching things, cleaning, mending, folding clothes, lighting fires, serving food, and pouring wine. If a skeletal servant leaves the structure it was created in for more than 7 consecutive days, it disintegrates into dust. Every 30 days on the advent of a full moon (or other celestial event of equal significance), an hour-long ritual may be performed by any character or hireling that can cast at least one necromancy spell. When the ritual is complete, it raises an additional five skeletal servants (if there are an adequate number of dead humanoid bodies entombed in this room) that join the others in the service of your structure. A structure may have a maximum number of functioning skeletal servants equal to 20 times the structures total number of room points.

Chapel

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: This room is under the effects of a permanent hallow spell, the details of which are decided upon when the construction of this room is completed. Intelligence (religion) checks made here that deal with the deity, philosophy, or religion the chapel is associated with have advantage. This expansion may be built multiple times, and each time a different religion or philosphy for the chapel must be chosen. If parishioners visit this room and provide tithes, this room generates an income of 10 gp x 4d6 every 30 days.

Clock Tower

Size Cost: 1 room point
Construction Cost: 675 gp
Construction Time: 7 days
Requirement: Knowledge of clockwork technology, a structure with at least 3 total room points.
Benefit: The presence of a clock tower greatly increases the efficiency of your workforce and thus your entire structure, requiring you to spend less on maintenance and wages to achieve the same effect. Reduce the total amount the structure’s hirelings must be paid by up to 50 gp weekly, you must still be paying at least half the wages.

Dining Hall

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: Every 7 days, a banquet may be held in this room. The owner of this structure rolls 1d4 (or 1d8 if the banquet includes a meal prepared by an individual with profiency in cook’s utensils), and divides out the result as points of inspiration to those present, only one point may given to any one individual. If the meal would have special, beneficial properties (as with the goodberry spell or similar), those properties apply to all individuals present that consume the meal.

Docks, Air

Size Cost: 2 room points
Construction Cost: 2,500 gp
Construction Time: 15 days
Requirements: Knowledge of air travel technology, a structure with at least 3 total room points.
Benefit: A number of airships equal to your structure’s total room points may moor safely at this room, which is likely a spire or free-floating dock. Mechanical Elevators and cranes are also present to raise and lower cargo. Roll once on the Merchants table at the end of this section. This merchant is present for 7 days, after which they depart and a new randomly-rolled merchant arrives, continuing this pattern every 7 days. This room generates an income of 15 gp x 2d10 every 30 days.

Docks, Planar

Size Cost: 2 room points
Construction Cost: 7,500 gp
Construction Time: 15 days
Requirements: Knowledge of planar travel technology, a structure with at least 3 total room points.
Benefit: A number of spelljammers or similar dimensional ships equal to your structure’s total room points may moor safely at this room, which is likely an immense hangar or free-floating dock built into a stable portal to another realm. Roll once on the merchants table, this merchant is present for 7 days, after which they depart and a newly rolled merchant arrives, conintuing this pattern every 7 days. This room generates an income of 20 gp x 2d8 in strange currency (such as electrum or fragments of astral diamonds every 30 days.

Docks, Water

Size Cost: 2 room points
Construction Cost: 2,500 gp
Construction Time: 15 days
Requirements: Structure must be adjacent to water.
Benefit: A number of ships equal to twice your structure’s total room points may moor safely at this room, which is likely a harbor or waterfront Roll twice on the Merchants table at the end of this section. These merchants are present for 7 days, after which they depart and two new randomly-rolled merchant arrives, continuing this pattern every 7 days. This room generates an income of 25 gp x 2d10 every 30 days

Escape Tunnel

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: A secret tunnel runs from a point in your structure you choose to another point outside within a mile, also of your choosing. This room automatically benefits from the Hidden improvement.

Factory

Size Cost: 1 room point
Construction Cost: 675 gp
Construction Time: 15 days
Benefit: A character or hireling that is proficient with tinkers tools may use the factory to craft automatons, when they do so they may halve the amount of time required to craft and repair automatons. This room is considered to always have tinkers tools in it. Additionally you may use this room to create a special type of Clockwork Servant, this construct counts as an unpaid skilled hireling. You may create a number of them equal to 2 x your total room points. If you own an armory they count as a Clockwork Watchman instead when fighting in defense of the city. The servants do as commanded by the owner of the structure and their allies, and stand motionless in place if commands conflict, waiting until new commands are given. If a Clockwork Servant leaves the structure it was created in for more than 7 consecutive days, it disintegrates into dust.

Garden

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: Contains an assortment of herbs and grown vegetables. Every 30 days, the garden provides enough ingredients to make 10 potions of common quality, 4 potions of uncommon quality, or one potion of rare quality. After the herbs have been picked, each potion must be brewed with a successful alchemist supplies check. The DC for the check is 10 for common potions, 15 for uncommon potions, and 20 for a rare potion. A failure destroys the gathered herbs used to brew that particular potion until they regrow after after another 30 days. Your DM may rule that certain potions are unable to be brewed with herbs from the garden. You may build this room more than once.

Graveyard

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: Dead bodies may be interred here, and suffer no degradation for the purposes of necromancy spells. If the graveyard is empty, it can be assumed to contain an additional 1d8 bodies every 7 days. When cast in this room by the ownder and their allies, the spells animate dead and create undead each create an addition undead minion of the lowest possible CR. Additionally, Intelligence (Arcana) checks made here that deal with necromancy or the dead have advantage.

Jails

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: You have cells available to securely hold a number of humanoids up to five times your structure’s total room points. Prisoners may only escape if they are unguarded, and either have access to this room;s key (five of which come with this room), or by using thieves’ tools to make four successful DC 15 Dexterity checks. This room is equipped for non-magical humanoids, and will not thwart magical attempts at escape unless the appropriate wards under the Warded improvement are purchased for this room.

Library

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: When taking at least an hour to perform an Intelligence (arcana, history, nature or religion) check to find specific knowledge within this expansion, you gain advantage on the roll. Even if you do not (or cannot) succeed, you can typically uncover a hint as to where this information may be found. Additionally a person performing the Research downtime activity only has to pay 50 gp instead of 100 for the initial fee.

Lighthouse

Size cost: 1 room point
Construction Cost: 675 gp
Construction Time: 7 days
Requirements: Structure must be adjacent to water.
Benefit: Ships travelling on water that are allied with the owner of this structure and are within a distance of this structure equal to two days of normal travel are able to navigate more accurately with the presence of a lighthouse. Within this distance, these ships can travel twice as fast without worrying about the dangers the sea presents, doubling their effective speed while not in combat.

Lodgings

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: This room may hold and house either and addtional 50 hirelings or individuals in communal bunks, or it may hold up to 24 hirelings or individuals in six private bedrooms, up to 4 persons per bedroom. You choose one of these options when you first build this room. If you build this room in a structure that can reasonable expect paying travelers, you choose to provide private bedrooms, and no more than four of your hirelings live in this room, this room then generates an income of 30 gp x 1d10 every 30 days. This room may be built multiple times. Any hirelings that are given rooms here only need be paid half the amount of wages.

Magical Enchanter

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: A spellcaster hireling or a character with the spellcasting or pact magic feature may make magic items, weapons, and armor here. Any magic item may be created here, excepting items that are potions or artifacts, see crafting for more details. This room counts as having an additional person assisting in the craft, when creating magic items.

Market Stalls

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: Choose three merchants from the merchants table at the end of this section. These merchants are in permanent residence at your structure, though the quality of their goods changes every 7 days. If your structure is located in an area that can reasonably expect trade, this room generates an income of 30 gp x 2d6 every 30 days. This structure may be built multiple times.

Mill

Size Cost: 1 room point
Construction Cost: 675 gp
Construction Time: 7 days
Requirements: one raw resource (wood, metal, grain, fish, wool, gems, or similar) harvested and under the control of the owner of this structure or their allies, within 7 days travel of the structure.
Benefit: If this room is fully staffed by at least 10 inskilled hirelings and at least 3 skilled hireling proficient in a relevant set of artisan’s tools, it can produce refined materials from available raw resources. If these raw resources are supplied, the mill can generate salable materials worth 100 gp x 1d10 every 30 days. These materials may be sold to interested buyers, consumed in place of hirelings wages if they are food, or used in place of gold cost for crafting, if applicable. This room may be built multiple times.

Poisoner’s Grotto

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: Every 30 days, this room provides enough ingredients to make a quantity of items (as listed) from one of the following groups:

Once the ingredients are harvested, they must be successfully brewed as a single batch with an alchemist’s supplies or poisoner’s kit check. This check’s DC is listed with the items it creates, and if this check fails, it destroys gathered ingredients used to brew the items until a new batch regrows after 30 days. You may build this room more than once.

Ritual Circle

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: Spells may be cast as rituals in half the usual time here without expending any components that do not have an associated cost in gold. If a ritual has components with a gold cost, this cost is halved when the ritual is performed in this expansion. While here, the owners of this structure and their allies have advantage on all rolls required by rituals.

Sewers

Size Cost: 1 room point
Construction Cost: 675 gp
Construction Time: 7 days
Benefit: Creatures that dwell within a structure containing this room lead healthier lives and live in a much more sanitary environment. As such, these creatures have advantage on saving throws made against disease and the poisoned condition as long as they are within 10,000 feet of the structure. Ocassionally, strange itmes wash up in the sewers. Every 30 days, rool 1d6. On a rool of 1 or 2, a random item from the trinkets table on pages 160-161 of the Players Handbook is found, intact and (mostly) clean.

Smithy

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: When you first make this room, choose a specific type of artisan’s tools, such as smith;s tools. These tools are always present in this room, and individuals that are proficient with these tools can create items in half the normal time while working in this room to craft a mundane item (see crafting). You may also place a skilled hireling in here to perform crafting for/with you, this hireling also counts as a Tools, Weapons, or Medium or Heavy Armor merchant (your choice) that is always present here. The quality of this merchant’s wares changes every 7 days. If such a hireling is assigned, this room generates an income of 15 gp x 1d10 every 30 days. This room may be built multiple times, but a different set of artisan;s tools must be chosen each time.

Siege Workshop

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: A team of at least 10 properly-skilled hirelings can build siege equipment here. The workshop may build one of the following options at any one time, the statistics for all of which are found in the Dungeon Master’s Guide, page 255:
Ballista. Takes 7 days, costs 500 gp.
Cannon. Takes 7 days (and knowledge of gunpowder), costs 750 gp.
Cauldron. suspended. Takes 7 days, costs 500 gp.
Mangonel. Takes 15 days, costs 1,500 gp.
Ram. Takes 7 days, costs 500 gp.
Siege Tower. Takes 30 days, costs 2,500 gp.
Trebuchet. Takes 30 days, costs 2,500 gp.
Your structure may only physically house a number of siege weapons equal to its total room points at any one time.

Stables

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: Your structure gains the ability to house and support horses or other animals trained to be used as mounts, and can hold four of these creatures for each unit of your structure’s maximum expansion units. Mounts that receive a long rest within this expansion have the movement speed increased by 10 feet for 24 hours afterward. This stable does not come equipped with mounts, and mounts must be acquired by other means.

Tavern

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: Taverns are a gathering place for those dispensing quests and rumors, and a typical trip to this tavern will dispense 1d4-1 of each every 7 days. Further,, the presence of a tavern gives the owner of this structure and their allies advantage on all Charmisma (persuasion) checks involving those who regularly use the tavern. This is generally expected to be almost all of those that live within the structure, as well as an assortment of those that live nearby. If at least one appropriately skilled hireling is stagged here, they count as an alcohol and refreshment merchant, and the wuality of their stock changes every 7 days. The tavern generates 2d10 kegs of alcohol worth 5 gp each every 30 days, or worth 10 gp each if the tavern is staffed for at least 7 days by a character or hireling proficient in brewer’s supplies. In addition to the kegs it creates, this room generates an income of 10 gp x 1d10 every 30 days if it is staffed by at least two hirelings.

Teleportation Rune

Size Cost: 1 room point
Construction Cost: 1,750 gp
Construction Time: 12 days
Requirements: A structure with at least 3 total room points and a character or hireling that can cast 5th level spells.
Benefit: When this rune is first created, choose a command word. Any creature that touches this rune and speaks its command word may instantly teleport to any other room of their choice in the same structure. Alternatively you may use your rune to teleport to another persons structure, provided they also have a Teleportation Rune room and you know what their command word is.

Theater

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: When on the stage, the owner and their allies gain advantage on all Charisma rolls. In addition, when someone on-stage makes a Charisma (persuasion, deception or performance) check with a result above 15, any of their allies present gain a point of inspiration. This latter benefit may only occur once every 7 days. Finally if the owner or allies are training in a new language, tool or skill profiency, they may halve the required learning time (after applying modifers).

War Room

Size Cost: 1 room point
Construction Cost: 625 gp
Construction Time: 7 days
Benefit: Soldiers friendly to the owner of this structure may have their journeys (of up to 7 days) planned within this room. Doing so effectively doublses the overland speed of these soldiers, causing them to complete the planned journey in half the normal time. In addition, when a structure that contains a war room is under attack, all creatures fighting in the structure’s defense add 1d4 to their attacks rolls to hit.

Modifying Your Rooms

If a room is already built it may be modified, the room becomes inactive until the modification has been completed. Or you may add these modifcations when initially constructing a room, in which case simply add the construction time for the modification onto that for the room. Some modifications have requirements, which the owner or at least one of the owner’s allies within the structure must be able to fulfill in order to build.

Extra-Dimensional

Requirements: A character or hireling that can cast 8th level spells
Construction Cost: 3,750 gp
Construction Time: 15 days
Benefit: This room’s door is actually a portal to a pocket dimension, containing the room itself. The laws of time and gravity in the expansion are yours to set, within limit, only once when you first modify the expansion. Gravity can be half to twice as strong, and time can move at half-pace to double time, realtive to the ouside. The room also have the immunity to scrying, tracking, and similar that being located on a different plane provides.

Hidden

Construction Cost: 1,250 gp
Construction Time: 7 days
Benefit: This modification may be added onto any room to hide it from view. The owner of the structure and any allies they designate know the secret to enter the hidden room. All others must first make a DC 15 Intelligence (investigation) check to iscover the presence of the a hidden chamber, followed by a DC 15 Dexterity (slight of hand) check to uncover how to enter, once they are aware aware of its presence.

Secret Passage

Construction Cost: 1,250 gp
Construction Time: 7 days
Requirements: At least two furnished rooms, a structure with at least 3 total room points.
Benefit: This modification is built in two rooms simultaneously, though it only requires one construction cost to be paid. A secret passage makes a hidden connection between these two rooms, behind walls, under floors and generally out of view. Similar to a hidden room, the owner of the structure and any allies they designate know how to enter this secret passage from either of its entrances, and can move freely between these two rooms. All others must first make a DC 15 Intelligence (ingestigation) check to discover the presence of a secret passage, followed by a DC 15 Dexterity (sleight of hand) check to uncover how to enter, once they are aware of it. You may build multiple secret passages into one room, but each passage must connect to a different room.

Trapped

Requirements: Varies (see below; none if none are listed)
Construction Cost: Varies (see below)
Construction Time: 7 days
Benefit: This rom contains one of the following traps, which you choose when you build this modification. Details on these traps may be found on pages 122-123 of the Dungeon Master’s Guide. This modification may be built multiple times in a single room for multiple traps.
Falling Net. Costs 750 gp, requires a character or hireling trained in Wisdom (survival)
Fire-Breathing Statue. Costs 1,250 gp, and requires a character or hireling that can cast at least 2nd level spells.
Pit, Simple. Costs 500 gp
Pit, Hidden. Costs 1,000 gp, requires a character or hireling trained in Dexterity (stealth) or Charisma (deception)
Pit, Locking. Costs 1,500 gp, requires a character or hireling trained in Dexterity (stealth) or Charisma (deception), and Dexterity (sleight of hand)
Pit, Spiked. Costs 2,000 gp, requires a character or hireling trained in Wisdom (survival). If the pit is also hidden or locking, it must also meet their requirements, above.
Poison Darts. Costs 1,250 gp, requires a character or hireling trained in Wisdom (survival)
Poison Needle. Costs 1,500 gp, requires a character or hireling trained in Wisdom (survival).
Rolling Sphere. Costs 2,000 gp, requires a character or hireling trained in Wisdom (survival)
Sphere of Annihilation. Costs 5,000 gp, requires a character or hireling that can cast at least 7th level spells.

Warded or Spell-Bound

Requirements: A character or hireling that can cast the listed spell.
Construction Cost: Varies (see below)
Construction Time: 7 days
Benefit: This room is constantly under the effect of one of the following spels, the details of which you decide when you build this modification and may only be altered later by rebuilding this modification and paying the cost a second time. These spells are always considered to fill the entire room and are cast at the lowest level possible, with the owner of the structure and those they designate considered to be the spell’s casters. Saves made against spells cast with this modification are made against a DC of 15. You may build this modification multiple times, choosing a different spell for each.
Alarm. Costs 500 gp
Animate Objects. Costs 1,500 gp
Antimagic Field. Costs 2,250 gp
Circle of power. Costs 1,500 gp
Magic Circle. Costs 1,000 gp
Reverse Gravity. Costs 2,000 gp
Unseen Servant. Costs 250 gp per unseen servant. This room contains up to 10 unseen servants who respond to the wishes of the owner and their allies.
Zone of Truth. Costs 750 gp. When you build this modification, choose whether it affects all creatures, the owner and their allies, or enemies of the owner.

Merchants and Traders

Some rooms will entice merchants to visit or take up residence at your structure, brining commerce to your doorstep. Whenever a room tells you to roll (or choose) on the merchants table, do so on the table below.

Whenever you roll or choose a merchant from the above table, also roll on the quality table, below, to determine the quality of their goods. Legendary merchants do not exist below medium quality, and should be rerolled until they have medium or above.

Based on the results of these tables the merchants will have different inventories (ask your DM), and will carry a different amount of gold or gems, either on them or in a secure location such as a trapped lockbox

Making More Money

Running a structure is an expensive enterprise, and one that can become unprofitable if not done with money in mind. Below are a few ways to help your structure generate a profit.

Tithes.
If your structure is one that draws daily visitors in the form of worshipers. you can demand a fee each day for the services they recieve. This could range from 1 sp for a poor man’s shrine to 5 gp daily for a maginificent cathedral. A shrine or temple may receive 50-250 visitors in a day. Keep in mind that higher prices may attract less visitors.

Tuition.
If your structure is one that draws daily visitors in the form of students, you can demand a fee each day for the services they receive. This could range from 5 sp a day for a tool proficieny school (such as teaching brewers supplies) to 10 gp daily for a world-class arcane education. A large college or school should expect a maximum of 100 students. Keep in mind that higher prices may attract less visitors.

Right of Passage.
Merchants and travellers must pay coin for the right to use toll roads near your structure. A small fine of 1 cp is typical of most toll roads, but some lucrative trade routes charge exorbitant fees of up to 5 gp. Traffic varies on most roads from 2 to 200 travelling groups a day depending on logistics and economic factors, and most merchants will do everything they can to avoid paying a pricey toll.

Protection.
Nearby villages could pay taxes for protection to a military presence in their region. Taxes could run from a reasonable 1 cp a day to an extreme 2 sp daily. The sizes of potential taxable population centers are detailed on pages 16-17 of the Dungeon Masters Guide. Take warning that peasants feeling taxes are unfair are very prone to violent revolt.

Other Sources.
As always, GMs remain open to player ideas, particularly on how to use a structure. Players will undoubtedly have ideas not covered here, and it is up to us to accomodate you however we can.

Source

http://walrock-homebrew.blogspot.com/2015/12/worldbuilding-option-fortresses-temples.html

Image – http://dndspeak.com/2017/12/100-city-quests/