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

Ultimate Undead Fortitude. If damage reduces the zombie colossus to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the zombie colossus raises to 50 hit points instead.

Undead Regeneration. The zombie colossus regains 20 hit points at the start of its turn if it has at least 1 hit point. If the zombie colossus takes radiant damage or damage from holy water, this trait doesn’t function at the start of the zombie colossus's next turn.

Motionless Mass. If the main body of the zombie colossus is killed or destroyed all of the zombies that were part of it die immediately.

Unusual Nature. The zombie colossus doesn’t require air, food, drink, or sleep.

Stench of Doom. Any creature that starts its turn within 60 feet of the zombie colossus must succeed on a DC 22 Constitution saving throw or take 16 4d8 poison damage. On a failed save, the creature is poisoned and can’t regain hit points until the end of its next turn. On a successful save, the creature is immune to its stench of doom for 24 hours

Multiattack. The zombie makes four Putrid Slam attacks.

Putrid Slam. Melee Weapon Attack: +11 to hit, reach 20 ft., one target. Hit: 25 5d8+11 necrotic damage.

Flesh Entomb (Recharge 5–6).  The Zombie Colossus flings a detached clump of corpses at a creature it can see within 60 feet of it. The target must succeed on a DC 18 Strength saving throw or take 16 4d10 bludgeoning damage, and if the target is a Large or smaller creature, it becomes entombed in dead flesh.

A creature entombed in the dead flesh is restrained, has total cover against attacks and other effects outside the dead flesh, and takes 14 6d6 necrotic damage at the start of each of its turns. A Humanoid reduced to 0 hit points by this damage dies and rises as a zombie immediately (see its stat block in the Monster Manual). The zombie acts immediately after the zombie colossus in the initiative count. The creature can be freed if the dead flesh is destroyed. The dead flesh is a Large object with AC 18, 60 hit points, and immunity to poison and psychic damage.

Hurl Zombie Mob (3/Day). The zombie colossus flings a detached clump of zombies led by one greater zombie (see their stat block in the Monster Manual and Tomb of Horrors) at an area it can see within 60 feet of it. Roll 1d10+5 to determine the number of zombies. If the result is a 1 the mob becomes a zombie clot (see its stat block in Van Richten’s Guide to Ravenloft).

Death Miasma (3/Day).  The zombie colossus releases noxious gas in a 60-foot-radius sphere centered on itself. Each creature in that area must make a DC 22 Constitution saving throw, taking 24 6d8 poison damage on a failed save, or half as much damage on a successful one. A Humanoid reduced to 0 hit points by this damage dies and rises as a zombie (see its stat block in the Monster Manual) 1 minute later. The zombie acts immediately after the zombie colossus in the initiative count.

The zombie colossus can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The zombie colossus regains spent legendary actions at the start of its turn.

Putrid Slam. Melee Weapon Attack: +11 to hit, reach 20 ft., one target. Hit: 25 5d8+11 necrotic damage.

Hurl Zombie Mob (3/Day)(Costs 3 Actions). The zombie colossus flings a detached clump of zombies led by one greater zombie (see their stat block in the Monster Manual and Tomb of Horrors) at an area it can see within 60 feet of it. Roll 1d10+5 to determine the number of zombies. If the result is a 1 the mob becomes a zombie clot (see its stat block in Van Richten’s Guide to Ravenloft).

Death Miasma (3/Day)(Costs 3 Actions).  The zombie colossus releases noxious gas in a 60-foot-radius sphere centered on itself. Each creature in that area must make a DC 22 Constitution saving throw, taking 24 6d8 poison damage on a failed save, or half as much damage on a successful one. A Humanoid reduced to 0 hit points by this damage dies and rises as a zombie (see its stat block in the Monster Manual) 1 minute later. The zombie acts immediately after the zombie colossus in the initiative count.

Move. The zombie colossus moves up to its speed