From publisher blurb:
From Jacob Blackmon comes a new creepy foe ready to menance your M&M game!
From the depths of the deepest underwater trench comes a horror unlike any ever seen. This monster might be the lost evolutionary link from when ancient humanity left the ocean to become land-dwelling creatures. Or this might be some sort of mutant human that decided land was not good enough and returned to the sea.
The gill creature is a humanoid monster that has strong piscean traits: webbed digits, clawed fingers, gills, large eyes, and a wide, fish-like mouth filled with sharp teeth.