Amalgamation of the Damned

Regenerative Bodies. The Amalgam regains 10 hit points at the beginning of each of its turns.

Legendary Resistance (3/Day). If the Amalgam fails a saving throw, it can choose to succeed instead.

Magic Resistance. The Amalgam has advantage on saving throws against spells and other magical effects. 

Soul consumer. When the Amalgam reduces a creature to 0 hit points, that creature must make a DC 15 Constitution saving throw or immediately take one death saving throw fail. If a creature fails a death saving throe while within 10 feet of the amalgam, the failure counts twice. If a creature dies while within 30 feet of the amalgam, their soul is consumed and the Amalgam heals a number of hit points equal to half their hit point maximum.

Comprised of the Damned. When the amalgam takes 50 or more damage from a single attack, a body gets ejected by the amalgam. The creature who hurt it must succeed on a DC 26 dexterity saving throw or take 15 (3d10) bludgeoning damage and fall prone.

All encompassing. The Amalgam cannot be flanked, and cannot be hit by opportunity attacks. When the amalgam takes an opportunity attack, they do not use their reaction. 

Multiattack. The Amalgam attacks three times with its swipe, any number of which can be replaced with a Consume.

Swipe. Melee weapon attack: +18 to hit, 16 (2d8 + 10) bludgeoning damage plus an additional 36 (8d8) Necrotic damage. Any creature hit by this attack is also grappled. While grappled in this way the creature is restrained. A creature that starts its turn grappled by the Amalgam takes 20 (4d8) Necrotic damage. The Amalgam can grapple up to three creatures at a time.

Consume. Melee weapon attack: +18 to hit, 36 (8d8) Necrotic damage. This attack can only target a creature grappled by the Amalgam. Any creature hit by this attack must succeed on a DC 20 Strength saving throw or be engulfed into the Amalgams body. While they are inside of the Amalgam, they are blinded, deafened, restrained, and take 10 bludgeoning damage at the start of every turn. When a creature starts its turn within the Amalgam, it must succeed on a DC 26 Wisdom saving throw or be incapacitated until the end of their current turn.

Wretched Gas of the Damned (Recharge 6). Every creature within 30 feet of the Amalgam must succeed on a DC 20 Constitution saving throw or become cursed until the end of the Amalgam's next turn. While curse din this way, the creature is paralyzed.

The Amalgam can take 3 legendary actions, choosing from the options below. Only one legendary action can be taken at a time and only at the end of another creature's turn. The Amalgam regains spent legendary cations at the start of its turn.

Swipe. The Amalgam takes a swipe attack.

Consume (Costs 2 Actions). The Amalgam makes a consume attack.

Body fling. Ranged weapon attack: +18 to hit, 25 (5d10) bludgeoning damage and the creature falls prone.

Body double (Costs 2 Actions). The Amalgam drops a corpse, which lashes out at a creature within 30 feet of the Amalgam. The creature must succeed on a DC 23 strength (Athletics) check or become grappled. At the start of the creature's turn, they take 15 (3d10) necrotic damage, and the creature's hit point maximum is reduced by the amount of necrotic damage taken.The Amalgam heals for half the damage this legendary action deals.