Frozen Stygia is ruled by Levistus, an archdevil known for offering bargains to those who face an inescapable doom.
Ability Score Increase. Your Charisma score increases by 2, and your Constitution score increases by 1.
Legacy of Stygia. You know the ray of frost cantrip. When you reach 3rd level, you can cast the armor of Agathys spell as a 2nd-level spell once with this trait and regain the ability to do so when you finish a long rest. When you reach 5th level, you can cast the darkness spell once with this trait and regain the ability to do so when you finish a long rest. Charisma is your spellcasting ability for these spells.