Dianoga, Adult

Armor Class 14 · Hit Points 105 (10d12 + 40) · Speed 15 ft., swim 60 ft.

Grasping Tendrils (Trait). The dianoga can have up to seven at a time. Each tentacle can be attacked (AC 20; 10 hit points; immunity to poison and psychic damage). Destroying a tentacle deals no damage to the dianoga, which can extrude a replacement tentacle on its next turn. A tentacle can also be broken if a creature takes an action and succeeds on a DC 16 Strength check against it.

Limited Amphibiousness (Trait). The dianoga can breathe air and water, but it needs to be submerged at least once every 4 hours to avoid suffocating.

Multiattack (Action). The dianoga can make three attacks: two with its tentacles and one with its bite.

Bite (Action). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d8 + 2) kinetic damage. If the target is a creature, it must succeed on a DC 15 Constitution saving throw against disease or become poisoned until the disease is cured. Every 24 hours that elapse, the target must repeat the saving throw, reducing its hit point maximum by 5 (1d10) on a failure. The disease is cured on a success. The target dies if the disease reduces its hit point maximum to 0. This reduction to the target's hit point maximum lasts until the disease is cured.

Tentacles (Action). Melee Weapon Attack: +6 to hit, reach 15 ft., one target. Hit: 11 (2d8 + 2) kinetic damage, and the target is grappled (escape DC 16). Until this grapple ends, the target is restrained.

Tentacle Slam (Action). The dianoga slams creatures grappled by it into each other or a solid surface. Each creature must succeed on a DC 14 Constitution saving throw or take 10 (2d6 + 3) kinetic damage and be stunned until the end of the dianoga's next turn. On a successful save, the target takes half the kinetic damage and isn't stunned.