Giant Octopus

The monster can breathe only underwater. It can hold its breath for 1 hour outside water.

Melee Attack Roll: +5, reach 5 ft. Hit: 2d6+3 Slashing damage. If the target is a Medium or smaller creature, it has the Grappled condition (escape DC 13) from all eight tentacles. While Grappled, the target has the Restrained condition.

Trigger: The monster takes damage while underwater. Response: The monster releases ink that fills a 10-foot Cube centered on itself, and the monster 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.