Ever play the Dungeon! computer game based on the board game?
I look back at Eludecia, the Succubus Paladin from the D&D 3.5 days.
I update her for Basic-era (B/X, BECMI) D&D and my plans for her in TWO different campaigns.
When a powerful wizard dies–truly, utterly, commits to the notion of their life coming to an end–they can cast one final, devastating spell against a single creature by digging into their final reserves of arcane power: their own soul.
Here are some nasty little curses for your NPCs (or players!) to utilize in their last moments.
Working on fleshing out an RPG/D&D character? Use conflicting motivations and goals to force difficult decisions and help flesh out who you want to be!