Blood Leech

Scent of Blood. Has advantage of all checks involving sense of smell. 

Blood Ritual. When this creature is summoned by the Blood Ritual spell, it obeys all commands of the summoner.

Gift of the Blood Queen. When this creature reaches 0 hit points, make a DC 17 constitution saving throw. If successful, it reconstitutes in blood, and regains 2d8 hit points.

Diving Leech. The leech lurches forward, jumping to attach itself to an enemy. The target must succeed on a DC 14 Dexterity saving throw or the leech becomes attached to their body, draining their blood dealing 2d6+4 necrotic damage. Restores 1d4+2 hit points.

Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., 1 target. Hit: 6 (1d6 + 3) piercing damage. Target must succeed on a DC 13 constitution saving throw or suffer 1d8+4 nature damage.