Shambling Mound

Whenever the monster is subjected to Lightning damage, it regains a number of Hit Points equal to the Lightning damage dealt.

The monster makes three Charged Tendril attacks. It can replace one attack with a use of Engulf.

Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 13 (2d4 + 4) Lightning damage. If the target is a Medium or smaller creature, the monster pulls the target 5 feet straight toward itself.

Strength Saving Throw: DC 23, one Medium or smaller creature within 5 feet. Failure: The target is pulled into the monster's space and has the Grappled condition (escape DC 14). Until the grapple ends, the target has the Blinded and Restrained conditions, and it takes 10 (3d6) Lightning damage at the start of each of its turns. When the monster moves, the Grappled target moves with it, costing it no extra movement. The monster can have only one creature Grappled by this action at a time.