Ceaseless Void

Invulnearbility. Ceaseless Void is immune to all damage from all sources as long as one dark energy that it controls is not yet destroyed. If it becomes vulnearble, all damage dealt to it is reduced to 1 regardless of bonuses. Ceaseless void is also immune to all on-hit effects.

Ceaseless Void. Ceaseless Void drags all creatures and objects that are Large or smaller 5 ft towards it at the end of each of Ceaseless Void's turns if it fails a DC 15 STR save. This save increases by 2 at 30 hp, 20 hp, and 10 hp. If they are pulled within 5 ft of Ceaseless Void, it can make a Cosmic Rend attack as a bonus action(once per turn). If they are pulled into the Ceaseless Void's space, they become trapped.

Ceaseless Void can have any numbrer of creatures trapped inside it. A trapped creature is blinded and restrained, and takes 55(10d10) force damage at the end of each of their turns. If a creature is reduced to 0 hit points by this damage, it dies. A creature can escape by making a DC 25 STR save, ending all conditions on it on a success and appearing in an unoccupied space within 5 ft  of Ceaseless Void(Ceaseless Void can still make a Cosmic Rend attack as a bonus action against it). Objects that are trapped in the Ceaseless Void are instantly destroyed with the exception of magic items and artifacts, which are freed if Ceaseless Void is destroyed.

Ghosting. Ceaseless Void can travel through solid material unless it chooses not to without disturbing the material it passes through.

Summon Dark Energies(Recharge 4-6). Ceaseless Void summons three dark energies, which appear in unoccupied spaces within 30 ft of it. A dark energy is a Medium typeless enemy, have AC 14, a flying speed of 40 ft, can hover, and have 55 hit points. A dark energy tries to ram a nearby enemy that Ceaseless Void can see. A creature who moves into its space takes 27(6d8) necrotic damage. These summons are not affected by Ceaseless Void's Ceaseless Void trait and are immune to all damage for the rest of the round in which they were summoned.

Cosmic Rend. Melee Spell Attack: +12 to hit, reach 5 ft., all creatures within 5 ft of it. Hit: 32(6d8 + 5) force damage. 

Laser Portal(Recharge 4-6). Ceaseless Void creates a Medum laser portal that lasts for 3 rounds. On the Ceaseless Void's initiative, it moves 10 ft and shoots a spread of lasers, forcing all creatures within 40 ft of it to make a DC 20 DEX save or take 22(4d10) force damage.

Dark Energy Ring(Recharge 6). Ceaseless Void creates a ring of invulnerable dark energies that lasts for one minute. These energies orbit 15 ft from a fixed point either on the ground or above it. A creature inside the ring does not take any damage, but if the creature moves into the space 5 ft outside of the 15 ft radius, it must make a DC 17 DEX save or take 36(8d8) necrotic damage. Large creatures make this save with disadvantage and Huge creatures or larger automatically fail the save.

Ceaseless Void 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. Ceaseless Void regains spent legendary actions at the start of its turn.

Move. Ceaseless Void moves up to half its speed without provoking any oppurtunity attacks.

Spatial Warp. Ceaseless Void makes one Cosmic Rend attack.

Teleport(Costs 2 Actions). Ceaseless Void magically teleports up to 60 ft in an unoccupied space it can see.