Anyway, here you go - killer bed sheets ahoy...
Sheet Phantom – Large Undead
Hpts: 88 (16d10) [16 - 160]
Speed: 30', Fly 30'
Proficiency Bonus: +3
Str: 17 (+3) Dex: 19 (+4) Con: 11 (+0) Int: 14 (+2) Wis: 12 (+1) Cha: 15 (+2)
Saving Throws: Dexterity +7, Wisdom +4
Skills: Perception +4, Stealth +10; Ghostly Movement
Damage Resistances: Acid; Piercing from non-magical weapons; Evasion
Damage Immunity: Poison, Bludgeoning from non-magical weapons; Evasion
Condition Immunity: Blinded, Poisoned, Intoxicated, Frightened, Unconscious, Exhausted
Senses: Blindsight 120' (Blind beyond this); Passive Perception: 14
Language: Those spoken in life
CR: 7 (2,900 xp)
Evasion: If the Sheet Phantom is exposed to an attack that deal half damage on a successful Dexterity saving throw, it suffers no damage on a save, and half on a fail.
Ghostly Movement: The Sheet Phantom adds twice its proficiency bonus to Stealth checks.
Shared Pain: Whilst the Phantom has a victim engulfed, half the damage it suffers is also suffered by the victim. This does not reduce the damage it suffers however
Engulfing Strike: Melee attack; Reach 10', One target; +7 to hit; Hit: 14 (3d6+4) Bludgeoning damage and Phantom wraps around the target (if they are medium sized or smaller) , restraining them. Restrained targets are immobilised and suffer 25 (10d4) points of Bludgeoning damage automatically at the start of their turns. Whilst engulfed, a character is restrained, blinded and silenced. They can, as an action attempt to break free (D.C. 15 Dexterity check or D.C.14 Strength check). Whilst the phantom has a victim engulfed it cannot Fly, and it's speed drops to 10'. It may still lash out with its Engulfing Strike attack, but can only restrain one victim at a time.
Create Spawn: Humanoids slain by the Engulfing Strike rise as Sheet Ghouls 24 hours later unless a Gentle Repose or Protection from Evil spell is cast on their remains.