If an opponent attacks with a unit that has Deflect and you cast Face Breaker without paying the Deflect cost, are any units stunned?

Ruling: You cannot cast Face Breaker without paying the Deflect cost. Deflect increases the cost of your spell or ability, and you cannot put it on the chain unless you also pay the Deflect cost.

Nuances:

• Face Breaker does not use the word "choose" or "target", but it still counts as choosing a game object in Riftbound's rules system
• Any instruction that tells you to do something with a single game object is considered a choice (and therefore subject to Deflect)
• This is different from Magic: The Gathering, where "target" must be explicitly stated