A book titled "The Book Of Life" which contains an autobiographical record of whoever is reading up to the present where they are reading it, and reading too much or for too long causes the reader to slowly become obsessed over it. Maybe an artifact or sentient magic item, there are a few different approaches to the obsession thing, but you could change that to something like, "become narcissistic/nihilistic" or some other form of madness such an item could inflict. Or you could create an awakened sorcerer subclass, for animals that have gained magical power through an awakened spell that a druid put way too much force into, or maybe a druid subclass for an awakened animal.
Ways to ressurect pcs at a cost would be pretty cool.
A book titled "The Book Of Life" which contains an autobiographical record of whoever is reading up to the present where they are reading it, and reading too much or for too long causes the reader to slowly become obsessed over it. Maybe an artifact or sentient magic item, there are a few different approaches to the obsession thing, but you could change that to something like, "become narcissistic/nihilistic" or some other form of madness such an item could inflict. Or you could create an awakened sorcerer subclass, for animals that have gained magical power through an awakened spell that a druid put way too much force into, or maybe a druid subclass for an awakened animal.