Black Leech

Multiattack. During it's action phase, the Black Leech can make 2 attacks, with preference for Drain Blood

Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., 1 target. Hit: 12 (2d8 + 3) Piercing damage. If this attack hits, the target is considered grappled until it makes a successful DC 15 acrobatics or athletics check

Drain Blood. Melee Weapon Attack: +8 to hit, reach 10 ft., 1 target. Hit: 7 (2d4 + 2) necrotic damage damage and your hit point maximum is diminished by the same amount.  That much health is restored as temporary HP.

Anticoagulant. As a reaction if the Black Leech is forced to release its grapple, it may force an anti-coagulant into the victim's system.  This victim makes a Constitution Saving Throw with a DC of 13 or it continues to take 2d6 + 2 Poison Damage at the beginning of its turn until it successfully