Blunderpuss

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

Quick Tentacles. The blunderpuss has advantage on Dexterity checks and can use its action to make a Dexterity (sleight of hand) check to unlock, open or disarm nonmagical doors, traps, chests and other similar objects.

Water Breathing. The blunderpuss can breathe only underwater.

Multiattack. The blunderpuss makes three melee attacks. It can forgo one of these for a barnacle attack instead.

Tentacle. Melee Weapon Attack: +7 to hit, reach 15 ft., one target. Hit: 10 (2d6 + 4) bludgeoning damage. If the target is a creature, it is grappled (escape DC 16). Until this grapple ends, the target is restrained.
The blunderpuss can grapple up to four medium sized creatures or one large sized or bigger creature. The blunderpuss's tentacles cannot be used to make attacks if it does not have enough free tentacles.

Swindle. Melee Weapon Attack: +7 to hit, reach 15 ft., one creature grappled by its tentacles. Hit: The blunderpuss takes one item being worn or carried by the target, Shoves it up to 10 feet away in a straight line. The target is no longer grappled by its tentacles.

Ink (1/Short Rest). A 20- foot-radius cloud of ink extends all around the blunderpuss 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 blunderpuss can use the Dash action as a bonus action. If used out of water, the blunderpuss creates a circle of radius 20-feet. This area is treated as difficult terrain. Whenever a creature other than the blunderpuss first enters, starts it's turn, or takes damage within the radius, it must succeed on a Dexterity saving throw of DC 13, falling prone on a failure.

Barnacle. Ranged Weapon Attack: +7 to hit, reach 120/480 ft., one target. Hit: 16 (2d12 + 4) bludgeoning damage. If the target is a creature, it must succeed on a DC 15 Strength saving throw or be knocked prone.

Shell Shield. Whenever another creature attacks or forces the blunderpuss to make a Dexterity saving throw, it can use its reaction to gain three-quarters cover. This benefit lasts until the end of that creatures turn. To do so, the blunderpuss must be holding its shell and the effect must be something it can see.