Illithasque (5e Creature)
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Gargantuan aberration (titan), lawful evil
Saving Throws Int +13, Wis +12, Cha +9
Legendary Resistance (3/Day). If the illithasque fails a saving throw, it can choose to succeed instead.
Magic Resistance. The illithasque has advantage on saving throws against spells and other magical effects.
Reflective Carapace. Any time the illithasque is targeted by a magic missile spell, a line spell, or a spell that requires a ranged attack roll, roll a d6. On a 1 to 5, the illithasque is unaffected. On a 6, the illithasque is unaffected, and the effect is reflected back at the caster as though it originated from the illithasque, turning the caster into the target.
Siege Monster. The illithasque deals double damage to objects and structures.
Innate Spellcasting (Psionics). The Illithasque's innate spellcasting ability is Intelligence (spell save DC 22). It can innately cast the following spells, requiring no components:
Multiattack. The Illithasque can use its Frightful Presence. It then makes five attacks: one with its bite, two with its claws, one with its horns, and one with its tail. It can use its Swallow instead of its bite.
Bite. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 36 (4d12 + 10) piercing damage. If the target is a creature, it is grappled (escape DC 20). Until this grapple ends, the target is restrained, and the illithasque can't bite another target.
Claw. Melee Weapon Attack: +19 to hit, reach 15 ft., one target. Hit: 28 (4d8 + 10) slashing damage.
Horns. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 32 (4d10 + 10) piercing damage.
Tail. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 24 (4d6 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 20 Strength saving throw or be knocked prone.
Frightful Presence. Each creature of the illithasque's choice within 120 feet of it and aware of it must succeed on a DC 17 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, with disadvantage if the illithasque is within line of sight, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the illithasque's Frightful Presence for the next 24 hours.
Swallow. The illithasque makes one bite attack against a Large or smaller creature it is grappling. If the attack hits, the target takes the bite's damage, the target is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside the illithasque, and it takes 56 (16d6) acid damage at the start of each of the illithasque's turns.
Tentacles. Melee Weapon Attack: +19 to hit, reach 5 ft., one creature. Hit: 15 (2d10 + 4) psychic damage. If the target is Gargantuan or smaller, it is grappled (escape DC 26) and must succeed on a DC 22 Intelligence saving throw or be stunned until this grapple ends.
Extract Brain. Melee Weapon Attack: +19 to hit, reach 5 ft., one incapacitated humanoid grappled by the illithasque. Hit: The target takes 63 (10d10 + 10) piercing damage. If this damage reduces the target to 0 hit points, the illithasque kills the target by extracting and devouring its brain.
Mind Blast (Recharge 5-6). The Illithasque magically emits psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 22 Intelligence saving throw or take 22 (4d8 + 4) 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 illithasque can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The illithasque regains spent legendary actions at the start of its turn.
Attack. The illithasque makes one claw attack or tail attack.
The material world has faced great dangers in its wake, Countless invasions from beasts from other worlds. However it always held the greatest trump card out of them all, The Tarrasque. This last resort beast can cause the destruction of civilizations and bring many invaders running back home. And when it is done it retreats deep underground to slumber again. However a group of mind flayers stumbled upon the sleeping creature in all its great glory. Seeing the opportunity to reclaim their kingdom with a mighty beast such as this they created a hive around it. When completed they built the gestalt pool around its head, granting one tadpole to wiggle its way into the creatures brain and start the ultimate process. It took decades but eventually the beast awoken once more, yet not as a weapon of the material realm but as a member of the illithid hive mind. Combining its mighty strength with illithid psionics it will lead the charge to once again bring all realms down on their knees to the illithids great empire.