Boss Fight: Shuluth the Ultitharid

The fourth and final boss of a darkness gathering adventure the mind flayer mastermind, Shuluth.  This was an interesting encounter.  Originally designed for 8 PCs only 4 turned up on the day.  The party also fought through the neo-otuygh random encounter, 2 urophions (solo) and then 1 urophion supported by mind flayer psychic warriors (nicknamed “Cid” and “Demon” by the PCs). Though no individual encounter threatened to kill them it wore them down slowly (Shuluth’s intention).

The party then decided to take a long rest in the dungeon not realising that A) Shuluth was nearby and B) Shuluth can sense them and knows what they are doing.  He decides to interrupt their rest and teleport in.

In this scenario, I decided that because he was fighting outside his actual den he lost his lair actions (this makes sense once you see them).  I also removed his legendary actions with the logic that he is both angry and upset that the PCs had completely dismantled his operation and that the elder brain is not going to be happy – his life was forfeit if he couldn’t kill these interfering PCs. Basically, he wasn’t thinking straight.  

Even with those changes, this was a deadly deadly fight for 4 level 16 PCs who had used a bunch of their resources already.  They did triumph in the end and won through but it was a hard fought (and fun) fight.

I am also using no-save effects more and more.  I did this a bit in Iron Gods but using it extensively in this adventure.

Sections in red are additions post game.

Large aberration, lawful evil
Armour Class 21 (resin battle armour)
Hit Points 400
Speed 40 ft.

20 (+5) 12 (+1) 15 (+2) 21 (+5) 19 (+4) 21 (+5)

Saving Throws INT +11, WIS +10, CHA +11, CON +8

Damage Vulnerabilities lightning (see Resin Battle Armor)
Skills Arcana+11, Insight+10, Perception+10, Stealth+7
Senses Darkvision120 ft., Passive Perception 18
Languages Deep Speech, Telepathy 2 miles, Undercommon
Challenge 20 (25,000 XP)

Chaos Theory. Shuluth seeks to find order in chaos and can force disadvantage on a chaos-touched creature to immediately reroll one attack roll, check, or save. Shuluth may use this ability once per round as a free action but otherwise is bound by the rules of a Reaction.

Creature Sense. Shuluth is aware of the presence of creatures within 2 miles of it that have an Intelligence score of 4 or higher. It knows the distance and direction to each creature, as well as each creature’s Intelligence score, but can’t sense anything else about it. A creature protected by a mind blank spell, a nondetection spell, or similar magic can’t be perceived in this manner.

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

Psionic Hub. If an elder brain establishes a psychic link with Shuluth, the elder brain can form a psychic link with any other creature the ulitharid can detect using its Creature Sense. Any such link ends if the creature falls outside the telepathy ranges of both the ulitharid and the elder brain. The ulitharid can maintain its psychic link with the elder brain regardless of the distance between them, so long as they are both on the same plane of existence. If the ulitharid is more than 5 miles away from the elder brain, it can end the psychic link at any time (no action required).

Psionic Celerity. Anytime a creature makes a saving throw against a psionic ability manifested by Shuluth the psionic power recharges and Shuluth gets his action back (that is the power is not used and Shuluth may act again).

Innate Spellcasting (Psionics). The ulitharid’s innate spellcasting ability is Intelligence (spell save DC 19). It can innately cast the following spells, requiring no components:

At will: detect thoughts, levitate
1/day each: confusion, dominate monster(use against fighter), eyebite (sleep or disadvantage), feeblemind (use against wizard), mass suggestion, plane shift (self only), project image, scrying, telekinesis (immobilize a target +11 vs STR – use against fighter).

Special Equipment: Resin Battle Armor. This enhanced dampsuit provides the following benefits to Shuluth – +6 AC, Damage Reduction of 10, Strength 20 (15 original), extends the reach of his tentacles by 5 feet to 15 feet, adding blades to the end of each tentacle allowing Shuluth to switch damage types to slashing for its tentacle attacks if it chooses and adds the multiattack action. It also provides environmental protection to Shuluth allowing it to ignore weather extremes that are natural in nature. It also removed Shuluth’s vulnerability to lightning.  

Multiattack. Shuluth uses Mind Blast (if available) and then makes six tentacle attacks.

Tentacles. Melee Weapon Attack:+11 to hit, reach 15 ft., one creature.
Hit: 27 (4d10 + 5) psychic damage. If the target is Large or smaller, it is grappled(escape DC 14) and must succeed on a DC 19 Intelligence saving throw or be stunned until this grapple ends. Shuluth has six tentacles it can grapple with. The creature is also infused with chaos theory for 1 minute and can end the effect on a DC 19 Intelligence check at the end of its turn.

Extract Brain. Melee Weapon Attack:+11 to hit, reach 15 ft., one incapacitated humanoid grappled by the ulitharid.
Hit: 55 (10d10) piercing damage. If this damage reduces the target to 0 hit points, the ulitharid kills the target by extracting and devouring its brain.

Mind Blast (Recharge 6). Shuluth emits psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 19 Intelligence saving throw or take 77 (16d8 + 5) psychic damage and be stunned for 1 minute or half as much damage on a successful save and not be stunned. A target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. The creature is also infused with chaos theory for 1 minute. If all targeted creatures save against this attack it automatically recharges.

Baleful Metamorphosis (1/Day). This psionic ability transforms a creature that Shuluth can see within 60’ into a new form for 1 hour. An unwilling creature must make a DC 19 Intelligence saving throw to avoid the effect. If the target succeeds at the saving throw this ability automatically refreshes and Shuluth may take another, different, action. The new form can be any beast whose challenge rating is equal to or less than the target’s (or the target’s level, if it doesn’t have a challenge rating). The target’s game statistics, including mental ability scores, are replaced by the statistics of the chosen beast. It retains its alignment and personality. Shuluth likes to turn pesky adventurers into sheep.

Alter RealityIf Shuluth would be struck by an attack it may use its reaction to teleport up to 10 feet away. The triggering attack misses.

Bloodied Mind Bomb. When first bloodied Shululths mind blast recharges and it can use it as a free action. The mind bomb version explodes in a 20 ft sphere centred on Shuluth. It otherwise stays the same. If this reaction triggers but Shuluth has already used its reaction this turn this instead becomes either a legendary action option or a new one off attack option (DM’s choice).

Chaos Theory. This is a free action once per round, see the related trait.

Shuluth 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. Shuluth regains spent legendary actions at the start of its turn.

  • Psion. Shuluth manifests a psionic power.
  • Psychic Warrior. Shuluth makes a tentacle attack.
    Forceful Submission (Costs 1 or 2 Actions). Shuluth may force an enemy that succeeds a saving throw to make that saving throw again at disadvantage. This legendary action can be used as a rider on Shuluth’s’ Mind Blast but this costs 2 actions.

Dim light bathes the room from the 10 alcove mirrors and the 40-foot-high ceiling and walls are carved in strange and unsettling imagery.

  • Far Realm Mirrors. Arranged around the perimeter of the north end of the room are a series of alcoves equipped with dark mirrors that swirl with dim, darkly multicoloured light. The mirrors are a psychic stain and distracting to the PCs. All characters in the room (or anytime a creature starts its turn adjacent to a mirror) is exposed to this hazard. Each creature must make a DC 13 Constitution saving throw or suffer a –2 to Intelligence saving throws and ability checks until they leave the lair, and the target is slowed until the end of its next turn. Alternatively, the target can make a second DC 13 Sanity saving throw to permanently avoid this hazard, but a failure causes a permanent loss of 1 Sanity points.
  • Strangely Carved Walls. Stretching across the back of this room is a freestanding wall carved with strange and unsettling patterns that coalesce into maddening scenes as one watches. It instils in nonaberrant creatures the desire to look away in horror. Those who gaze on anyway are subject to far realm visions. Each creature who is not averting their eyes and acting blindly must make a DC 13 Wisdom saving throw taking 20 psychic damage on a fail, and the target is dazed (save ends). On a success the target only takes 5 psychic damage.
  • Aberrant Pool. Much like the rest of its lair, the room is filled to about a foot in water teeming with mind flayer tadpoles. Any nonaberrant creature that enters or starts its turn in the pool takes 3 (1d6) psychic damage as well as being exposed to far realm cackle fever on a failed DC 13 Constitution saving throw.

Lair Action

  • Twisted Mirror. There is only one lair action with multiple options. Three of the Far Realm Mirrors are twisted mirrors and each round on initiative count 20 (losing ties) will summon a random far realm creature – (1-2) Vicar of the Cosmos, (3-4) Celestial Children or (5-6) Celestial Centipede. These creatures disappear when the mirrors are destroyed (not disabled). The mirrors are destroyed when Shuluth is killed.


This human-shaped creature has an octopus-like head with six lashing tentacles. It is clad head to foot in a form-fitting suit bolted with plates.

Cranium Rats.  The “All For One” cerebral rat swarm who is an ally of Ebrietes the Adversary will arrive during the second round of combat and aide the PCs.

Round 1. “You can hear the splashing of many tiny feet and multiple “pew pew” sounds as something moves towards your location”

Round 2 (after Shuluth has his turn). “The sound you heard earlier is revealed to be a swarm of rats with exposed braincase glowing with psionic power.  The little buggers are zapping the mind-flayer tadpoles as they come with glee.  They swarm into the room and start blasting Shuluth with their tiny mind-rays.  It doesn’t seem to hurt Shuluth but it definitely annoys him”

All players gain a single boon die and a single bane die is cancelled (if any) for the rest of the fight.

Far Realm Cackle Fever. Far realm cackle fever is an empowered form of cackle fever and has an instantaneous incubation period. All infected creatures gain 1 level of exhaustion on a failed DC 13 Constitution saving throw. At the start of each round make a DC 13 Constitution saving throw or become incapacitated with laughter for 1 minute. Any nonaberrant creature who sees a victim of this laughter must also make a saving throw or contract the disease.


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