Haunting Aura. The guecubu’s presence is unnerving and distracting. Any creature that is not a Construct or Undead that finishes a short or long rest within 60 feet of the guecubu must succeed on a DC 14 Wisdom saving throw or derive no benefit from the rest. If a creature's saving throw is successful, the creature is immune to the guecubu's Haunting Aura for the next 24 hours.

Incorporeal Movement. The guecubu can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.

Invisibility. The guecubu is invisible.

Sleep Touch. Melee Spell Attack: +6 to hit, reach 5 ft., one target. Hit: 5 (1d4 + 3) necrotic damage. If the target isn’t a Construct or an Undead, it must succeed on a DC 14 Wisdom saving throw or fall asleep and remain unconscious for 1 minute. The target awakens if it takes damage or another creature takes an action to wake it.

Possession (Recharge 6). One sleeping Humanoid that the guecubu can see within 5 feet of itself must succeed on a DC 14 Charisma saving throw or be possessed by the guecubu; the guecubu then disappears, and the target is incapacitated and loses control of its body. The guecubu now controls the body but doesn’t deprive the target of awareness. The guecubu can’t be targeted by any attack, spell, or other effect, and it retains its alignment, Intelligence, Wisdom, Charisma, and immunity to being charmed and frightened. It otherwise uses the possessed 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 guecubu ends it as a bonus action, or the guecubu is forced out by an effect like the dispel evil and good spell. When the possession ends, the guecubu reappears in an unoccupied space within 5 feet of the body. The target is immune to this guecubu’s Possession for 24 hours after succeeding on the saving throw or after the possession ends.

Spellcasting. The guecubu casts one of the following spells, requiring no material components and using Charisma as the spellcasting ability (spell save DC 14):

At will: catapult, detect thoughts
3/day: telekinesis