Hold Breath. While out of water, the octopus can hold its breath for 30 minutes.
Maneuvers. The octopus uses maneuvers (maneuver save Difficulty 11). It has 2 stamina dice which are d8s, a dice limit of 1, regains all expended stamina dice when it finishes a long rest, and regains half its total stamina dice when it finishes a short rest. It knows the following maneuvers:
Underwater Camouflage. The octopus has advantage on Stealth checks made while underwater.
Water Breathing. The octopus can breathe only underwater.
Tentacles. Melee Weapon Attack: +3 to hit, reach 1 m. Hit: 1 bludgeoning damage.
Ink Cloud (Recharges after a Short or Long Rest). A 1-meter 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 without using an action.
As an action, you can make a melee weapon attack and a Brawn check to grapple the creature.
You can add the stamina die to the attack’s damage (add half if you miss by 4 or less) for each additional stamina die expended.
As an action, you can use the Dash action. If you move at least 4 meters straight toward a creature, you can make a melee weapon attack against it. Add the stamina die to the attack’s damage (add half if you miss by 4 or less).
You can increase the damage for each additional stamina die expended.