I don't know where i got this from, or if i made it up. But i have state bloc i never implemented.

The Silence (5e Creature) The Silence Medium aberration, neutral evil

Armor Class 15 (natural armor) Hit Points 45 (10d8) Speed 30 ft.

STR 10(+0) DEX 13 (+1) CON 11 (+0) INT 18 (+4) WIS 18 (+4) CHA 17 (+3)

Saving Throws Int +7, Wis +6 Skills Deception +5, Stealth +5, Intimidation +5, Perception +6, Persuasion +3 Damage Resistances lightning; bludgeoning, piercing, and slashing from non-magical attacks Damage Immunities: necrotic, Psychic Senses Truesight 30 ft., darkvision 60 ft., passive Perception 14 Languages: Deep speech, telepathy 120 ft. Challenge 4 (1,100 XP)

Magic Resistance. The Silence has advantage on saving throws against spells and other magical effects.

Amnesia. Whenever a creature is no longer able to see a silence a mark appears on their arm, legs, body, or face signifying that they have seen the silence, then must make a DC 15 Wisdom saving throw. On failure, the creature is charmed and is incapacitated and unaware of its surroundings, though it can still hear you. The target then forgets ever seeing any silence, and and any memories 10 minutes prior. On Success you remember the Silence, and take 2 (1d4) psychic damage.

Out of Sight. Innately, the Silence exist in its ethereal form. It steps through for the brief of moments to perform an action. Creatures who are not “Silence” can only see it when they are looking directly at it, or if they have succeeded on a previous wisdom saving throw, and know where it is.

Innate Spellcasting (Psionics). The silence's innate spellcasting ability is Intelligence (spell save DC 15, +7 to hit with spell attacks). The silence can innately cast the following spells, requiring only verbal components: At will: chill touch, lightning lure, suggestion

ACTIONS Multi-attack. The silence makes two attacks with its claws.

Claw. Melee Weapon Attack: +2 to hit, reach 5 ft., one creature. Hit: 6 (2d6) piercing damage, plus 7 (3d4) necrotic damage. The target must succeed on a DC 15 Constitution saving throw or look away from the silence (causing the Amnesia feature to trigger).