Black Slaad

Dark Star. If the slaad dies, its body creates a dark star which cannot be destroyed except by dispel magic (8th level version). The slaad reforms from the dark star after 1d10 days, reviving with all its Hit Points.

Entropic Aura. The slaad is shrouded in magical darkness to a radius of 30 feet. Each creature that is not a construct or undead that ends its turn within 15 feet of the slaad takes 14 (4d6) force damage.

Magic Resistance. The slaad has Advantage on saving throws against spells and other magical effects.

Regeneration. The slaad regains 10 Hit Points at the start of each of its turns if it has at least 1 Hit Point.

Multiattack. The slaad makes two Chaos Blade attacks.

Chaos Blade. Melee Attack Roll: +12, reach 10 ft. Hit: 20 (2d12 + 7) Slashing damage plus 14 (4d6) Force damage. Until the start of the slaad's next turn, the target has a condition determined by rolling 1d4: on a 1, Charmed; on a 2, Frightened; 3, Poisoned; on a 4, Incapacitated.

Spellcasting. The slaad casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 19):

At will: Detect Magic, Detect Thoughts, Fly, Greater Invisibility (self only), Mage Hand, Major Image, Tongues

3/day each: Dispel Magic (level 5 version), Finger of Death, Modify Memory, Plane Shift

1/day each: Mental Prison, Power Word Kill, Reality Break, Weird

Summon Slaadi (1/Day). The slaad summons 1d4 death slaadi. A summoned slaad appears in an unoccupied space within 60 feet of the black slaad, acts as an ally of the black slaad, and can't summon other slaadi.

Shape-Shift. The slaad shape-shifts into a Small or Medium Humanoid, or it returns to its true form. Other than its size, its game statistics are the same in each form. Any equipment it is wearing or carrying isn’t transformed.

Temporal Shunt. In response to a creature which the slaad can see making an attack roll or starting to cast a spell, the slaad casts Temporal Shunt.