Huge Aberration, lawful neutral
Armor Class 15 (natural armor)
Hit Points 123 (13d12+39)
Speed fly +30, walk +0, hover true
Challenge 7
Skills arcana +7, nature +7, history +7, insight +6, perception +6
Damage Resistances cold, fire
Damage Immunities poison
Condition Immunities blinded, paralyzed, petrified, poisoned, prone
Senses blindsight 120 ft. (blind beyond this radius), passive Perception 16
Languages Deep Speech, Undercommon, telepathy 120 ft.
Source: Tome of Beasts 2 · OGL/Open
False Appearance. While the crystalline monolith remains motionless, it is indistinguishable from a giant crystal.
Magic Resistance. The crystalline monolith has advantage on saving throws against spells and other magical effects.
Powerful Mind. The crystalline monolith has advantage on Intelligence saving throws and ability checks.
Innate Spellcasting (Psionics). The crystalline monolith's innate spellcasting ability is Intelligence (spell save DC 15). It can innately cast the following spells, requiring no components: At will: detect magic, detect thoughts, mage hand, silent image 3/day each: clairvoyance, hypnotic pattern, stinking cloud, telekinesis 1/day each: confusion, dominate person, suggestion
Multiattack. The crystalline monolith makes two slam attacks or two mind spear attacks. If both slam attacks hit a Large or smaller target, the target must succeed on a DC 14 Constitution saving throw or begin to turn to crystal and be restrained. The restrained creature must repeat the saving throw at the end of its next turn, becoming petrified on a failure or ending the effect on a success.
Slam. Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 11 (2d8 + 2) bludgeoning damage.
Mind Spear. Ranged Spell Attack: +7 to hit, range 30 ft., one target. Hit: 14 (4d6) psychic damage.
Psychic Burst (Recharge 5-6). The crystalline monolith emits a burst of psychic energy in a 30-foot cone. Each creature in that area must succeed on a DC 15 Intelligence saving throw or take 28 (8d6) psychic damage and be stunned for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
The crystalline monolith can take 3 legendary actions, choosing from one of the options below. Only one legendary action can be used at a time and only at the end of another creature’s turn. The crystalline monolith regains spent legendary actions at the start of its turn.
Detect. The crystalline monolith makes a Wisdom (Perception) check.
Teleport (Costs 2 Actions). The crystalline monolith magically teleports up to 120 feet to an unoccupied space it can see.
Cast a Spell (Costs 3 Actions). The crystalline monolith casts a spell from its list of innate spells, expending a daily use as normal.