Neverwinter Nights 2: Mask of the Betrayer -- the spirit eater curse. The best execution of a harmful curse giving you powers, while also becoming increasingly problematic the more you used those powers. It even solved many balancing issues from the main game by severely limiting resting, something that could definitiely benefit BG3.
I loved it, and I really wish Larian had taken some inspiration from that mechanic.
Omg, I didn't even think about Mask of the Betrayer. Yes. That system was very good. It was always a hard choice, do I want this powerful ability and risk possibly dying from not being able to consume enough spirits?
The more you used the Curse the more powerful you became but this also made you need to consume more spirits. Also using the abilities also made your hunger go down faster but the abilities were scaled so well that using them made the game easier but the game also became harder because of the hunger level.
Edit: Also the more you used the Curse the less control over it you had.
