Can Facebreaker be played if there is no friendly unit at a battlefield, or if the friendly unit is already stunned?

Ruling: Facebreaker requires both a friendly unit and an enemy unit to be at the same battlefield as valid targets when played. You can target an already stunned friendly unit (it just won't be stunned again), but you cannot play Facebreaker if no friendly unit is present at all.

Sequence:

• Check that both a friendly unit and enemy unit are at the same battlefield
• If both targets are valid, the card can be played
• Resolve as much as possible (e.g., if friendly is already stunned, only the enemy gets stunned)

Nuances:

• You cannot use Facebreaker to stun only your own unit without an enemy present
• You cannot use Facebreaker to stun only an enemy unit without a friendly unit present
• A friendly unit that is already stunned is still a valid target; the card will resolve and stun the enemy unit