Mortal Reminder is a Warlock passive feature unique to The Great Old One subclass that Frightens creatures upon a critical hit.
Description
When you land a Critical Hit against a creature, that creature and any nearby enemies must succeed a Wisdom Saving Throw or become Frightened until the end of their next turn.
Condition: Frightened
Duration: 1 turn
- Cannot move. Frightened entities also have
Disadvantage on 
Ability checks and 
Attack rolls.
How to learn
Classes:
- Class level 1: Great Old One