𝓟𝕒𝔯𝓽𝘺𝓰𝖔𝙚𝓻𝘴 =) (Backrooms)

Ultimate Shell. The Partygoer has an AC of 25 as long as it is not in berserker mode.

Separate organs. The Partygoer's arms are separate from the entities and have the following statistics:

Partygoer's arm (x2)
Armor Class 14
Hit Points 20 (4d8 + 4)
Speed 0 ft.

STR 14 (+2) DEX 18 (+4) CON 12 (+1)
INT 0 (-5) WIS 0 (-5) CHA 0 (-5)

Senses blindsight 30 ft.
Languages -

Actions
Devouring suction. The arm uses its teeth and suction cups at its end to reduce the flesh to pulp and suck it up. Melee Weapon Attack: +8 to hit, reach 10 ft., one target.
Hit: 14 (5d4+ 4) damage, the arm regains half the damages in HP. If the target falls under 10 HP, they suffers of the Partygoer's sickness.

Berserker mode. When the Partygoer loses both arms, it opens its shell and four giant centipede get out of it, two ghostly arms also emerge. The AC of the Partygoer is reduced to 16.

Multiattack. The Partygoer can use two spectral claws and one bad influence.

Spectral Claws (Berserker Mode Only). Melee Attack Roll: +8, reach 10 ft. Hit: 20 (8d4 + 4) Necrotic damage, if the target's HP fall under 10, they suffer of the Partygoer's sickness.

Bad Influence (Berserker Mode Only). The target must succeed a constitution saving throw (DD 14) or suffer the Partygoer's sickness.