From publisher blurb:
Excrement and waste aren’t just disgusting, they’re a vessel of death. While most tend to forget this fact, feces is the end product of people and animals eating things that were once alive. And when a necromancer forgets? The results can be unexpected and dire. Born from the residue of powerful necromantic spells, the Waste Slime is an undead pile of filth driven to kill by a hunger that it can’t understand and never satisfy. Unable to eat the flesh of the living, it will nonetheless slay anyone who slips within its reeking grasp.
Waste slimes arise from horrid sewers, latrines, and befouled wells. While less common, waste slimes can also arise from stagnant bogs, marshes, or ponds.