Octopus

Small beast · CR 0

Armor Class 12

Hit Points 3 (1d6)

Speed swim 30 ft., 5 ft.

STR 4 -3

DEX 15 +2

CON 11 +0

INT 3 -4

WIS 10 +0

CHA 4 -3

Skills perception +2, stealth +4

Senses darkvision30 ft. , passive Perception 12

Traits

Hold Breath.: While out of water, the octopus can hold its breath for 30 minutes.
Underwater Camouflage.: The octopus has advantage on Dexterity (Stealth) checks made while underwater.
Water Breathing.: The octopus can breathe only underwater.

Tentacles. Melee/Ranged Weapon Attack: +4 to hit.: Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 1 bludgeoning damage, and the target is grappled (escape DC 10). Until this grapple ends, the octopus can't use its tentacles on another target.
Ink Cloud (Recharges after a Short or Long Rest).: A 5-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.