Giant Octopus

Hold Breath. While out of water, the octopus can hold its breath for 1 hour.

Underwater Camouflage. The octopus has advantage on Dexterity (Stealth) checks made while underwater.

Water Breathing. The octopus can breathe only underwater.

Actions

Tentacles. Melee Weapon Attack: +5 to hit, reach 15 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage. If the target is a creature, it is grappled (escape DC 16). Until this grapple ends, the target is restrained, and the octopus can’t use its tentacles on another target.

Ink Cloud (Recharges after a Short or Long Rest). A 20-- foot-radius cloud of ink extends all around the octopus if it is underwater. The area is heavily obscured for 1 minute, although a significant current can disperse the ink. After releasing the ink, the octopus can use the Dash action as a bonus action.

Water Breathing. The octopus can breathe only underwater. It can hold its breath for 1 hour outside water.

Actions

Tentacles. Melee Attack Roll: +5, reach 10 ft. Hit: 10 (2d6 + 3) Bludgeoning 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.

Reactions

Ink Cloud (1/Day). Trigger: The octopus takes damage while underwater. Response: The octopus releases ink that fills a 10-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.