Blindspooker

Limited Invisibility. The blindspooker and anything it is wearing or carrying is invisible to any creatures that do not have their eyes closed, but becomes visible to any creature that closes its eyes, even in darkness. The blindspooker is invisible to blindsight, but is visible to any Blinded creatures. Creatures can choose to open or close their eyes at the beginning and end of their turns, but are Blinded to all other phenomena as long as they have their eyes closed.

Spider Climb. The blindspooker can climb up difficult surfaces, such as across ceilings, without needing to make an ability check.

Slash. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (2d6) slashing damage. 

Boo! When a creature that could not previously see the blindspooker becomes able to see it, and the blindspooker is within 30 feet of the creature, the blindspooker can use its reaction to try and scare the creature. The targeted creature must succeed on a DC 14 Wisdom saving throw or be Frightened for one minute. If a creature frightened in this way loses sight of the blindspooker, they cannot move in any direction. Creatures frightened in this way may repeat this saving throw at the end of each of their turns, ending the effect for themselves on a success. Any creature that succeeds on their saving throw becomes immune to this effect for the next 24 hours.