Necrotic Blood. A creature within 5 feet of the lurker takes 5 (1d10) necrotic damage whenever it hits the abyssal lurker with a melee attack that deals piercing or slashing damage.

Multiattack. The lurker makes four tentacle attacks. Up to four of these attacks can be replaced by either fling or draining crush, one replacement per tentacle grappling a creature.

Tentacle. Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 21 (3d8 + 6) piercing damage, and the target is grappled (escape DC 18) if it is a Huge or smaller creature. Until this grapple ends, the target is restrained, and the lurker can’t use the same tentacle on another target. The abyssal lurker has 8 tentacles.

Fling. One creature grappled by a tentacle is flung 60 ft in a random direction. They must make a DC 18 Dexterity saving throw or take 24 (4d10) bludgeoning damage, half as much damage on a successful save.

Draining Crush. One creature grappled by a tentacle of the abyssal lurker must make a DC 18 Constitution saving throw. On a failed save, the target takes 30 (5d10) bludgeoning damage, and the lurker regains half as many hit points. Half as much damage on a successful save. 

Ichor Spray: As a reaction, the lurker can release a spray of ichor, covering all hostile creatures within a 15 ft radius. Affected creatures must succeed on a DC 18 Dexterity saving throw or take 8 (2d6) poison damage and have disadvantage on all attacks until the start of their next turn. No effect on a successful save.