Waterwoe

Caustic Death. When the waterwoe drops to 0 hit points, its body disintegrates into the water surrounding it, releasing caustic liquids stored in its body. The water within 100 feet of the waterwoe when it dies become harmful for 1 minute. Any creature that begins its turn in the affected water takes 7 (2d6) acid damage at the start of their turn.

False Appearance. While the waterwoe remains motionless, it is indistinguishable from a mass of aquatic plants.

Grasping Vines. The waterwoe can have up to ten vines at a time. Each vine can be destroyed with 5 points of slashing or cold damage (AC 13). Destroying a vine deals no damage to the waterwoe, which can extrude a replacement vine on its next turn unless the waterwoe has taken cold damage since its last turn. A vine can also be broken if a creature takes an action and succeeds on a DC 17 Strength check against it.

Multiattack. The waterwoe makes two attacks with its vines.

Vines. Melee Weapon Attack: +9 to hit, reach 50 ft., one creature. Hit: The target takes 16 (2d10 + 5) piercing damage, and it is grappled (escape DC 17). Until this grapple ends, the target is restrained, and it takes 33 (10d6) acid damage at the start of each of its turns. The waterwoe can't use the same vine on another target.