As an action on a turn, a creature can force a facedown with an opponent. Each creature makes an opposing Intimidation or Deception check (the creature’s choice). A creature cannot attempt to start a Facedown if it is not proficient in Deception or Intimidation. Creatures with expertise in either skill can initiate Facedowns as a bonus action.
On a tie, nothing happens. Otherwise, the loser must either back down or gain a -3 to all d20 rolls made against that creature until it has defeated that creature.
Creatures immune to the Frightened Condition cannot be affected by Facedowns but can still win a Facedown if prompted.