Huge Aberration, chaotic evil
Armor Class 18 (natural armor)
Hit Points 253 (22d12+110)
Speed walk +40, climb +30
Challenge 16
Saving Throws con +1, int +8, wis +6
Skills perception +1
Damage Resistances poison, radiant; nonmagic B/P/S attacks not made w/adamantine weapons
Damage Immunities psychic
Condition Immunities charmed, frightened
Senses darkvision 120', tremorsense 60', passive Perception 16
Languages understands all but can't speak, telepathy 120'
Deathlights. When a creature that can see sovereigh's glowing antennae starts its turn within 30' of it sovereign can force it to make a DC 18 Wis save if sovereign isn't incapacitated and can see the creature. If save fails by 5+ creature is stunned until the start of its next turn. Otherwise creature that fails is incapacitated and its speed is reduced to 0 until start of its next turn as it remains transfixed in place by the lights. Unless surprised creature can avert its eyes to avoid the save at start of its turn. If creature does so it can't see sovereign until start of its next turn when it can avert again. If creature looks at sovereign in the meantime it must immediately save.
Illumination. Its antennae shed dim light in a 5 ft. radius. Radius increases to 20' while at least one creature is incapacitated or stunned by Deathlights. At start of its turn if no creatures are incapacitated or stunned by Deathlights sovereign can suppress this light until start of its next turn.
Inscrutable. Immune to any effect to sense its emotions or read its thoughts as well as any divination spell it refuses. Wis (Insight) checks made to ascertain sovereign's intentions or sincerity have disadvantage.
Legendary Resistance (3/Day). Choose to succeed failed save.
Magic Resistance. Advantage: spell/magic effect saves.
Spider Climb. Difficult surfaces even ceilings no ability check.
Sinuous Form. Provided there is suitable room to accommodate its bulk can squeeze through any opening large enough for a Small creature.
Multiattack. One Bite and two Slams. It can make one Tail in place of its Bite.
Bite. Melee Weapon Attack: +12 to hit, 5 ft., one target, 25 (4d8+7) piercing damage + 11 (2d10) poison.
Slam. Melee Weapon Attack: +12 to hit, 10 ft., one target, 23 (3d10+7) bludgeoning damage.
Tail. Melee Weapon Attack: +12 to hit, 10 ft., one target, 26 (3d12+7) slashing damage. If target is a Large or smaller creature it is grappled (escape DC 18). Until the grapple ends the target is restrained and sovereign can't use its tail on another target.
Consume Soul (Recharge 5-6). Chooses up to three creatures it can see within 60' of it that are incapacitated or stunned by Deathlights. Each target: 55 (10d10) psychic (DC 18 Wis half). Creature stunned by Deathlights has disadvantage on this save. Sovereign then regains hp equal to half total psychic dealt. A Humanoid slain by this rises 1d4 rounds later as a zombie under sovereign's control unless Humanoid is restored to life or its body is destroyed. Sovereign can have no more than thirty zombies under its control at one time.
Spellcasting (Psionics). Cha (DC 18) no spell components: At will: detect thoughts mage hand (the hand is invisible)3/day ea: dimension door telekinesis1/day: hallucinatory terrain (as an action)
Move. The cave sovereign moves up to its speed with o provoking opportunity attacks.
Telekinetic Reel. Magically pulls incapacitated or stunned creature by its Deathlights it can see up to 20' straight toward it.
Cast a Spell (2). Uses Spellcasting.
Tail Attack (2). Makes one Tail attack.
Source: Tome of Beasts 3 · OGL/Open