Octopus

The octopus can move through a space as narrow as 1 inch without expending extra movement to do so.

The octopus can breathe only underwater.

Melee Attack Roll: +4, reach 5 ft. Hit: 1 Bludgeoning damage.

Trigger: A creature ends its turn within 5 feet of the octopus while underwater. {@actResponse} The octopus releases ink that fills a 5-foot Cube centered on itself, and the octopus moves up to its Swim Speed. The Cube is Heavily Obscured for 1 minute or until a strong current or similar effect disperses the ink.