Darkmantle

Small

Monstrosity

Unaligned

11

22 (5d6 + 5)

2m, fly 6m

16 (+3)

12 (+1)

13 (+1)

2 (-4)

10 (+0)

5 (-3)

Stealth +3

Blindsight 12m, passive Perception 10

1/2 (100 XP)

The darkmantle can't use its blindsight while deafened.

While the darkmantle remains motionless, it is indistinguishable from a cave formation such as a stalactite or stalagmite.

Melee Weapon Attack: +5 to hit, reach 1m, one creature. Hit: (1d6 + 3) bludgeoning damage. The darkmantle attaches to the target If the target is Medium or smaller and the darkmantle has advantage on the attack roll, it attaches by engulfing the target's head, and the target is also blinded and unable to breathe while the darkmantle is attached in this way.
While attached to the target, the darkmantle can attack no other creature except the target but has advantage on its attack rolls. The darkmantle's speed also becomes 0, it can't benefit from any bonus to its speed, and it moves with the target.
A creature can detach the darkmantle by making a successful DC 13 Strength check as an action. On its turn, the darkmantle can detach itself from the target by using 1m of movement

A 3m radius of magical darkness extends out from the darkmantle, moves with it, and spreads around corners. The darkness lasts as long as the darkmantle maintains concentration, up to 10 minutes (as if concentrating on a spell). Darkvision can't penetrate this darkness, and no natural light can illuminate it. If any of the darkness overlaps with an area of light created by a spell of 2nd level or lower, the spell creating the light is dispelled.