In the original adventure the boss creature was a yah-thalgaad an ascended form of the neh-thalgaa. Paizo doesn’t have rights to use the mind-flayer which this adventure is custom built for. As I run a home campaign I have no such restrictions so I added a bunch of mind-flayer cronies to the adventure as well as replacing the boss yah-thalgaad with this boss mind-flayer. Thematically it fit perfectly I also think it worked better than just facing neh-thalgaa after neh-thalgaa as the original adventure had – which is otherwise excellent by the way.
During the battle the characters managed to paralyse it for 1 round getting past its magic resistance and dispel its levitate spell before using telekinesis to take away its Moschen’s Sphere. His mind blast kept the fighter on ice most of the battle though his dominate monster ability failed due to the fighter having a protection from evil spell activate. He almost ate the brain of the monk twice before being forced to teleport away… and then being sucked back by a divine intervention call from the cleric which only had an 11% chance of working – he rolled a 01. Not a good day for Dweller-In-Dark-Places.
Armour Class 19 (yah-thalgaad breastplate) + psionic carapace (+3 (1d6) psychic damage per hit if using light weapons or unarmed).
Hit Points 275 (55d8 + 55)
STR 11 (+0) DEX 12 (+1) CON 12 (+1)
INT 19 (+4) WIS 17 (+3) CHA 17 (+3)
Saving Throws lnt +10, Wis +7, Cha +7
Skills Arcana +9, Deception +8, Insight +8, Perception +6, Persuasion +6, Stealth +4
Senses darkvision 120ft., passive Perception 16
Languages Aklo, Deep Speech, Undercommon , telepathy 120ft.
Challenge 14 (11,500)
Command Disease. As a bonus action, a Dweller-in-Dark-Places can cause a disease or infection currently afflicting a creature within 30 feet to quicken and activate, forcing the afflicted creature to immediately attempt a saving throw against the disease’s effects. Those who fail immediately suffer the disease’s effects. These additional saving throws count against those one must succeed at to recover from a disease, so it’s possible for a victim to be cured by succeeding at enough saving throws. Any creature that has been affected by a Dweller-in-Dark-Places command disease ability (whether or not the creature succeeded at the saving throw this ability triggered) has disadvantage against any mind-affecting spell or effect generated by the Dweller-in-Dark-Places in the next minute.
Magic Resistance. The mind flayer has advantage on saving throws against spells and other magical effects.
Psionics. The mind flayer’s innate spellcasting ability is Intelligence (spell save DC 15). It can innately cast the following spells, requiring no components:
At will: detect thoughts, levitate
1/day each: dominate monster, teleport (self only), plane shift (self only)
Dweller-in-Dark-Places 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 Dweller-in-Dark-Places regains spent legendary actions at the start of its turn.
Detect. The Dweller-in-Dark-Places makes a Wisdom (Perception) check.
Tentacles. Dweller-in-Dark-Places makes a powerful tentacle attack.
Forceful Submission. (Costs 2 Actions). Dweller-in-Dark-Places 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 Dweller-in-Dark-Places’ Mind Blast and Illusion of Pain attacks.
Powerful Tentacles. Melee Weapon Attack: +8 to hit, reach 5 ft., one creature.
Hit: 20 (3d10 + 4) psychic damage. If the target is Medium or smaller, it is grappled (escape DC 15 with disadvantage) and must succeed on a DC 18 Intelligence saving throw or be stunned until this grapple ends.
Extract Brain. Melee Weapon Attack: +8 to hit, reach 5 ft., one incapacitated humanoid grappled by the mind flayer.
Hit: The target takes 55 (10d10) piercing damage. If this damage reduces the target to 0 hit points, the mind flayer kills the target by extracting and devouring its brain.
Illusion of Pain (Recharge 5-6). The Dweller-in-Darkness may create the illusion that a 20-foot radius area centered on itself is filled with writhing, barbed tentacles. Creatures who fail a DC 18 Intelligence saving throw are immobilized and take 22 (4d8 + 4) psychic damage (as do any creatures that first enter the area) and are immobilized 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. On a successful save the creature takes half-damage and is not immobilized.
Mind Blast (Recharge 6). The mind flayer psionically emits psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 18 Intelligence saving throw or take 68 (16d8 + 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. On a successful save the creature takes half-damage and is not stunned.
Alter Reality. If Dweller-in-Dark-Places would be struck by an attack it may teleport up to 10 feet away. The triggering attack misses.
This human-shaped creature has an octopus like head with four lashing tentacles. It is clad in ornate, heavy armour and wields a strange floating orb in one of its slimy hands (Legacy: Moschen’s Orb).