Sources
CR
Type
Size
Alignment
Movement

Voalsh

Medium Aberration, Lawful Evil

Armor Class 15 (breastplate)
Hit Points 156 (24d8 + 48)
Speed 0 ft., fly 30 ft. (hover)
STR
11
+0
DEX
12
+1
CON
15
+2
INT
21
+5
WIS
17
+3
CHA
18
+4
Saving Throws INT +9, WIS +7, CHA +8
Skills Arcana +9, Insight +7, Perception +7, Stealth +5
Damage Resistances psychic
Condition Immunities Blinded, Charmed, Frightened, Prone
Senses darkvision 120 ft., truesight 15 ft., passive Perception 17
Languages Deep Speech, telepathy 120 ft., Undercommon
Challenge 11 (7,200 XP)

Traits

Legendary Resistance (3/Day). If Voalsh fails a saving throw, it can choose to succeed instead.

Magic Resistance. Voalsh has advantage on saving throws against spells and other magical effects.

Spellcasting

Spellcasting (Psionics). Voalsh casts one of the following spells, requiring no spell components and using Intelligence as the spellcasting ability (spell save DC 17):

At will: detect magic, detect thoughts, mage hand (the hand is invisible)

1/day: plane shift (self only)

3/day each: clairvoyance (as an action), dispel magic

Actions

Multiattack. Voalsh makes two Tentacle attacks.

Tentacle. Melee Weapon Attack: +9 to hit, reach 5 ft., one creature. Hit:21 (3d10 + 5) psychic damage. If the target is Medium or smaller, it has the grappled condition (escape DC 17) and must succeed on a DC 17 Intelligence saving throw or have the incapacitated condition until the grapple ends.

Extract Brain. Melee Weapon Attack: +9 to hit, reach 5 ft., one incapacitated Humanoid grappled by Voalsh. Hit:55 (10d10) piercing damage. If this damage reduces the target to 0 hit points, the mind flayer kills it by extracting and devouring its brain.

Unleash Void (Recharge 5–6). Voalsh opens a rift into the Far Realm, centered on a point the mind flayer can see within 60 feet of itself, and a tentacle lashes across creatures near the rift. Each creature other than mind flayers within 30 feet of the rift must make a DC 17 Intelligence saving throw, after which the tentacle disappears and the rift closes. On a failed save, a creature takes 18 (4d8) cold damage from the rift plus 18 (4d8) psychic damage from the tentacle and has the stunned condition for 1 minute. On a successful save, a creature takes half as much damage only. A stunned creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Reactions

Warp Reality. When hit by an attack roll, Voalsh gains a +4 bonus to its AC against that attack roll, potentially causing it to miss. Then the mind flayer, along with any equipment it is wearing or carrying, magically teleports up to 60 feet to an unoccupied space it can see.