Magic of Velantis
Here in Velantis the weave is strong and all have access to it.
As such all beings regardless of class, have access to wizard cantrips, you know a number of them equal to your intelligence modifier. Intelligence is the ability used for casting these spells, unless you already have caster levels in a different class, then use the ability for that class instead. (eg bards cast with charisma)
Additionally those who truly master the weave are able to cast spells beyond that of beings in many other worlds, unlocking the power of the long lost 10th level spell, a level of power that was banned by mystra in the world of Toril.
You gain your first 10th level spell slot at level 19, if your class can already learn 9th level spells. However you must learn 10th level spells from spellbooks found throughout the world. Casting a 10th level spell requires an additional cost, part of your life essence, as such you are required to sacrifice 50,000 experience (returns a level 20 character to the start of level 19).
There will also be Epic magic available to such casters upon reaching level 20.
Increased Mana Pool
Another thing of note is that we will be using a variant on spell points rather than the standard spell slot rule of 5e.
This means that a level 1 spell uses 1 spell point, a level 2 spell uses 2 spell points and so on. Similarly the amount of spell points you have is equal to the amount of spell slots you would of had, so a level 1 spell slot provides you with 1 spell point, a level 2 slot provides 2 spell points.
For example a level 10 Wizard would have 41 spell points.
People have also found they are able to merge spells into a new single spell.
To do so, you must know both the spells to begin with, then spend a week researching how each spell interacts with the weave. after this week the new spell will be castable to you, and any whom you teach it too.
The new spell will have the effect of both spells, though the specifics of which will need to be discussed with a DM. The new spell will be added to the expanded spell list, but will require a lesson from one who can already cast it for others to learn. This spell will also be named after you. Much as Acid Arrow used to be called Melfs Acid Arrow, and Hideous Laughter was once Tasha’s Hideous Laughter.
Image – https://www.deviantart.com/slyth/art/Mystra-Remade-5217814