Black Slaad

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 three Chaos Rend attacks.

Chaos Rend. Melee Attack Roll: +14, reach 5 ft. Hit: 20 (2d10 + 8) Slashing damage plus 10 (3d6) Necrotic damage. Until the start of the slaad’s next turn, the target has a condition determined by rolling 1d6: on a 1, Charmed; on a 2, Frightened; on a 3, Poisoned; on a 4, Incapacitated; on a 5, Stunned;
or on a 6, Petrified.

Arcane Destruction. The slaad targets one magical object worn or carried by a creature
within 10 feet of itself. Dexterity Saving Throw: DC 24, the creature with the object. Failure: The object takes a −1 penalty to the AC it offers (armor) or to its attack rolls (weapon). Armor is destroyed if the penalty reduces its AC to 10, and a weapon is destroyed if its penalty reaches −5. If the object is neither armor nor a weapon, it loses 1d4 charges. The object is destroyed if it doesn't have charges, or if its number of remaining charges is reduced to 0.

Entropic Spittle. Ranged Attack Roll: +14, range 60 ft. Hit: 15 (2d6 + 8) Acid damage and
the target is coated in acidic spittle. Until the spittle is cleaned off of the target, the target’s Speed is reduced by 10 feet and then takes 3 (1d6) Acid damage at the start of each of their turns. The target, or an ally within 5 feet of the target, can take an action to clean the spittle from the target. The spittle turns into a chalky substance and flakes off of the target after 10 minutes, ending the effect.

Spellcasting. The slaad casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 16):

Summon Self (1/Day). The slaad summons 2d4 copies of itself from different timelines to aid it in battle. Each copy of the slaad appears in a space within 60 ft. chosen by the slaad. Each copy rolls its own Initiative, and all the copies share Hit Points with the slaad who summoned them. The copies remain for 1 hour, or until the slaad who summoned them is destroyed.

Summon Slaadi (3/Day). The slaad attempts to summon other slaadi to aid it in battle.
The slaadi summoned are determined by rolling 1d10: on a 1-2, no slaadi are summoned; on a 3-5, 2d4 Green Slaadi are summoned; on a 6-7, 1d6 Gray Slaadi are summoned; on a 8-9, 1d4 Death Slaadi are summoned; or on a 10, 1d2 White Slaadi are summoned.

At Will: Animate Objects, Mirror Image, Invisibility (self only), Blur, Darkness (90 ft. radius), Dispel Magic,
3/day: Lightning Bolt, Fireball, Finger of Death, Circle of Death
1/Day Each: Power Word Kill, Circle of Death, Power Word Stun, Disintegrate (level 9 version)

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

Arcane Consumption. The slaad casts Counterspell,in response to the spell’s trigger, using the same spellcasting ability as Spellcasting. If a spell is successfully countered by the slaad, the spell slot used to cast that spell is consumed and the slaad regains Hit Points equal to the level of the consumed spell slot