The Silence (5e Creature)
From D&D Wiki
Medium aberration, neutral evil
Saving Throws Int +7, Wis +6
Forget. Whenever a creature is no longer able to see a silence the target makes a mark on their arm, signifying that they have seen the silence. The target then forgets ever seeing the silence, and must make a DC 15 Constitution saving throw. On a failed save, the target takes 2 (1d4) psychic damage and staggers back 5 feet. On a successful save, the target takes half as much damage and does not stagger.
Innate Spellcasting. 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
Multiattack. The silence makes two attacks with its claws. Alternatively, it makes one attack with its claws and casts a spell.
Claw. Melee Weapon Attack: +3 to hit, reach 5 ft., one creature. Hit: 8 (2d6 + 1) 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 Forget feature to trigger).
No one really knows where the Silence came from. No one knows that the Silence even exist. For when you look away, you forget ever having seen the silence. While not a physically intimidating creature, the Silence are one of the most feared creatures to come across. Silent to their last breaths, they never give anything to remember them by. Disappearing into the night, they leave no trace of their existence. If you see them, you won't know. If they kill you, they will never find them. You will have died with no trace of an existence.