Colossal Octopus (5e Creature)
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Gargantuan beast, unaligned
Hold Breath. While out of water, the octopus can hold its breath for 1 hour.
Water Breathing. The octopus can breathe only underwater.
Multiattack. The octopus makes two attacks with its tentacles.
Tentacle. Melee Weapon Attack: +11 to hit, reach 20 ft., one target. Hit: 20 (4d6 + 6) bludgeoning damage. If the target is a creature, it is grappled (escape DC 18). Until this grapple ends, the target is restrained. The octopus has eight tentacles, each of which can grapple one target.
Ink Cloud (Recharges after a Short or Long Rest). An 80-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.
A colossal octopus lurks in the deepest ocean trenches, snatching prey and dragging it to its doom using its long tentacles.