Bloodsucking Worm

Amphibious. The worm can breathe air and water.

Poisonous Body. When a creature touches the worm or hits it with a melee attack while within 5 feet of it takes 4 (1d8) poison damage, plus 3 (1d6) acid damage.

Multiattack. The worm attacks once with Constrict, and once with Blood Drain. If it uses this action, both attacks must be against the same target.

Blood Drain. Melee Weapon Attack: +6 to hit, reach 10 ft., one creature. Hit: 12 (2d8 + 3) piercing damage plus 4 (1d8) poison damage, and the target is grappled (escape DC 15) by the worm. While the target is grappled, at the start of each of the worm's turns, the target loses 20 (5d6 + 3) hit points due to blood loss, and the worm regains half of the damage dealt. The worm can detach itself by spending 5 feet of its movement. Creatures that don't have blood in their bodies or don't need it, such as most undead and constructs, are immune to the blood loss effect in this attack.

Constrict. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 13 (3d6 + 3) bludgeoning damage plus 13 (3d8) poison damage plus 3 (1d6) acid damage, and the target is grappled by the worm (escape DC 15). While grappled, the target is also restrained and at the start of each of the worm's turns, the grappled target takes an extra 10 (2d6 + 3) bludgeoning damage plus 9 (2d8) poison damage plus 2 (1d4) acid damage.