Gremishka

Gremishkas are the vicious products of mistakes made by novice spellcasters seeking to create life. The results are cat-sized, magically unstable creatures with a taste for the trappings of magic—particularly spellbooks, spell components, familiars, and the like. Gremishkas delight in tormenting magic-users, holding vicious grudges against those who gave them life as they infest the walls of spellcasters’ homes or the surrounding lands.
Despite their feral appearances, gremishkas are cunning creatures. They might imitate the sounds of whimpering children or wounded animals to coax victims into tight quarters. While they favor attacking spellcasters, gremishkas are opportunistic hunters and lash out at anything they think they can overwhelm—or just get a bite of.
Gremishkas have an unstable relationship with magic. Spells cast near a gremishka might rebound onto those nearby or cause the monster to explode, its scaly chunks rapidly reforming into duplicate gremishkas. These spontaneously created swarms can rapidly turn a single annoying gremishka into a chittering, magic-reflecting wave of teeth and claws.
They are extremely hazardous in the magic-rich environment of the Bibliopolis, and should be destroyed on sight.
See Van Richten’s Guide to Ravenloft for more.