Name: Brollachan
Medium aberration, chaotic evil
Armor Class: 14 (natural armor)
Hit Points: 105 (14d8 + 42)
Speed: 30 ft., climb 30 ft.

STR 18 (+4)
DEX 16 (+3)
CON 16 (+3)
INT 6 (-2)
WIS 10 (+0)
CHA 6 (-2)

Skills: Stealth +6, Perception +4
Damage Resistances: Cold, Fire, Poison
Senses: Blindsight 60 ft., passive Perception 14
Languages: understands Common but can't speak
Challenge: 6 (2,300 XP)

        Amorphous. The Brollachan can move through a space as narrow as 1 inch without squeezing.
        Invisibility in Fog. The Brollachan is invisible while in mist, fog, or similar weather conditions.
        Shapechanger. The Brollachan can use its action to polymorph into a form that resembles a humanoid creature, a beast, or a monster with a challenge rating equal to or lower than its own. Its statistics, other than its size, are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.

Actions
        Multiattack. The Brollachan makes two slam attacks.
        Slam. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) bludgeoning damage.
        Possession (Recharge 5-6). One humanoid that the Brollachan can see within 5 feet of it must succeed on a DC 14 Wisdom saving throw or be possessed by the Brollachan; the Brollachan then disappears, and the target is incapacitated and loses control of its body. The Brollachan now controls the body but doesn't deprive the target of awareness. The Brollachan can't be targeted by any attack, spell, or other effect, except ones that would dispel it. It retains its Intelligence, Wisdom, and Charisma scores, as well as its understanding of Common. It otherwise adopts the target's statistics, but doesn't gain access to the target's knowledge, class features, or proficiencies. The possession lasts until the body drops to 0 hit points, the Brollachan ends it as a bonus action, or the Brollachan is forced out by an effect like the dispel evil and good spell. When the possession ends, the Brollachan reappears in an unoccupied space within 5 feet of the body.

Description: The Brollachan is a creature from Scottish folklore that is said to be shrouded in mist or fog, making it difficult to see or describe its physical appearance. However, some accounts describe it as a shapeless, black mass with glowing eyes or as a blob-like creature that can change its shape.

In some stories, the Brollachan is said to be a malevolent creature that feeds on human flesh and can possess or control those who come into contact with it. In other tales, it is portrayed as a misunderstood creature that is seeking help or redemption.

Despite its elusive and mysterious nature, the Brollachan is a well-known figure in Scottish folklore and continues to capture the imagination of those interested in the supernatural and the unknown.