Mutagenic corpse

Eating flesh from a mutagenic corpse grants a living character a random mutation and makes an undead character rot. If the flesh is rotten, the likelihood of it being a bad mutation is much higher. Eating mutagenic flesh provides no nutrition.

Using Fulsome Distillation on a mutagenic corpse grants you a potion of mutation, which gives you three mutations. It's useful to stash these as a medicine of last resort in case you wind up with many bad mutations and lack a potion of cure mutation, as the mutations they grant often negate existing ones. You may wind up even worse off, but it's a better than fair gamble, and you can accumulate many of these potions by the time mutations become common.