Necrotic Absorption. Whenever the undead shambling amalgamation is subjected to necrotic damage, it take no damage and regains a number of hit points equal to the necrotic damage dealt.

Turn Resistance. The undead shambling amalgamation has advantage on saving throws against any effect that turns undead.

Multiattack. The undead shambling amalgamation makes two empowered slam attacks. If both attacks hit a Medium or smaller target, the target is grappled (escape DC 14), and the undead shambling amalgamation uses Consume on it.

Empowered Slam. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) bludgeoning damage and 7 (2d6) necrotic damage.

Consume. The undead shambling amalgamation consumes a Medium or smaller creature grappled by it. The consumed target is blinded, restrained, and unable to breathe, and it must succeed on a DC 14 Constitution saving throw at the start of each of the mound's turns or take 13 (2d8 + 4) bludgeoning damage. If the mound moves, the consumed target moves with it. The mound can have only one creature consumed at a time.