Medium fiend (yugoloth), neutral evil

Armor Class: 17 (natural armor)

Hit Points: 162 (25d8 + 50)

Speed: 30 ft , fly: 30 ft , can hover

STR

20 +5

DEX

14 +2

CON

14 +2

INT

21 +5

WIS

16 +3

CHA

18 +4

Saving Throws: Dex +7, Int +10, Wis +8, Cha +9

Skills:

Deception +9, Insight +8, Perception +8

Damage Resistances: cold, fire, lightning; bludgeoning, piercing, and slashing from nonmagical attacks

Damage Immunities: acid, poison

Condition Immunities: charmed, poisoned

Senses:

truesight 120 ft., passive Perception 18

Languages: all, telepathy 120 ft.

Challenge Rating: 14 ( 11,500 XP)

Proficiency Bonus: +5

Actions

Multiattack. Shemeshka uses Arcane Flux or Spellcasting. She then makes one Claw attack or one attack with her Razorvine Tiara.

Arcane Flux. Shemeshka causes a surge of arcane energy to burst around one creature she can see within 120 feet of herself. The target must make a DC 18 Dexterity saving throw. On a failed save, the target takes 45 (7d12) force damage and has the incapacitated condition until the end of its next turn. On a successful save, the target takes half as much damage only.

Claw. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 10 (2d4 + 5) slashing damage plus 14 (4d6) poison damage.

Razorvine Tiara. Melee Weapon Attack: +10 to hit, reach 15 ft., one target. Hit: 10 (3d6) slashing damage plus 9 (2d8) necrotic damage. If the target is a creature, it must succeed on a DC 15 Constitution saving throw, or its speed is halved and it has disadvantage on attack rolls and saving throws until the end of its next turn.

Spellcasting. Shemeshka casts one of the following spells, requiring no material components and using Intelligence as the spellcasting ability (spell save DC 18):

At will: Alter Self, Darkness, Invisibility (self only), Mage Hand, Prestidigitation

2/day each: Detect Thoughts, Dimension Door, Suggestion

1/day each: Banishment, Contact Other Plane (as an action), Mind Blank

Bonus Actions

Teleport. Shemeshka teleports, along with any equipment she is wearing or carrying, up to 60 feet to an unoccupied space she can see.

Reactions

Fell Counterspell (3/Day). Shemeshka utters a magical word to interrupt a creature she can see that is casting a spell. If the spell is 5th level or lower, it fails and has no effect. If the spell is 6th level or higher, Shemeshka makes an Intelligence check (DC 10 + the spell’s level). On a success, the spell fails and has no effect. Whatever the spell’s level, the caster gains the poisoned condition until the end of its next turn.