Blighted Heart

Detect Pulse. The blighted heart can sense the presence and location of any creature within 300ft of it, regardless of interposing barriers, unless the creature is a construct, undead or protected by a nondetection spell. 

Blood Frenzy. The blighted heart has advantage on melee attack rolls against any creature that doesn’t have all its hit points.

Tentacle. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 6 (1d10 + 1) piercing damage, and the Blighted Heart attaches to the target. The attached Blighted Heart moves with the target whenever the target moves, requiring none of the Blighted Heart’s movement. The Blighted Heart can detach itself by spending 5 feet of its movement on its turn. A creature, including the target, can use its action to detach a Blighted Heart.

Heartripper. The Blighted Heart makes one tentacle attack with advantage against a creature it is attached to. If the attack hits, the creature takes the tentacle's damage and must succeed on a DC 13 Constitution saving throw. If they fail, the Blighted Heart inflicts an additional 18 (3d10) piercing damage and the creature is stunned until the start of their next turn. If the tentacle attack roll resulted in a critical hit, the target has disadvantage on their saving throw.

Devour. When a creature dies within reach of the Blighted Heart, it may use its reaction to mutilate the corpse and restore a number of hit points equal to half the creature's maximum hit points.