Necromass (5e Creature)
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Gargantuan undead, chaotic evil
Saving Throws Dex +10, Con +19
Necromass I. A necromass is a hulking mass of melded undead. This conglomeration of undead is extremely hard to stop. Every time it takes necrotic damage it heals a number of hit points equal to the damage dealt. Also, for every 10 damage it takes, 5 groups of 2d4 zombies drop down to the ground around it and underneath it. These zombies are as found in the monster manual. Radiant, Fire and Cold damage do not spawn these groups of zombies. The necromass has seperate hit point pools for each of its 4 leg-arms, and it's head. The legs each have 350 hit point, and the heart has 125 hit points. Destroying the heart requires being on top of or above the necromass, meaning over 85 ft up. Upon the hearts destruction the entire necromass falls apart into 10d100 zombies. If the heart was killed with fire, cold or radiant damage then no zombies are spawned as the effect (Light, frost, or fire) spreads through all of the remaining bodies in the mass.
Necromass II. A necromass, being a mass of undead is not something that you want to touch. Any creature within 5 feet of the necromass must make a strength save DC 26, and on a failed save is restrained and takes 10d8 piercing and 5d12 slashing damage. They may repeat this save every round. Also anyone who tries to exit this 5 ft range must make the same save at DC 20.
Necromass III. The main body of the necromass may only move up to 80 ft from any of its leg-arms. Its torso is also 20 ft off the ground.
The can take 8 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 regains spent legendary actions at the start of its turn.
Scream(Uses 2 Legendary Actions). All creatures in a 150 ft radius centered on the main torso must make a constitution saving DC 20. On a failed save they take 10d8 thunder damage and are deafened for 3 rounds. On a successful saving throw they take half damage.
Step. One of the 4 limbs of the necromass moves up to 60 ft, but may only go up to 80 ft from the main body at any time. It may step onto any solid surface and not fall, and any creature under the leg-arm(a 15 by 15 cube) must make a DC 20 dexterity saving throw, and on a failed save be stepped on taking 12d12 bludgeoning damage. On a successful save they dodge and move up to their remaining movement speed away from it. If they don't have movement speed remaining or they are stepped on then they must make a DC 26 strength save as with the feature necromass II. If they fail and are restrained then they are caught under the foot until it moves again or they succeed on a DC 26 strength save.
A massive mass of zombies, its head directly on top constantly open letting out deadly screams. The inside of the necromass, accessible only through the mouth, holds a massive heart of melded flesh(that can be seen through the mouth) that when killed destroys the entire necromass. The limbs of the necromass are twisted multi-jointed pseudo leg-arms that are also masses of melded together flesh.