Pay to crack the crate and pray to the drop table. Legendary (rare) grants a random apex card. Epic grants a bishop and 30 seconds. Rare grants a knight. Common grants a pawn. But almost one crate in three is a mimic that bites off your weakest piece and leaves you shaken for two turns.
You draft Loot Box in Buff mode. Instant: it takes effect the moment you draft it.
As a pieces card, it summons, revives, promotes, or converts a piece.
“The next one is guaranteed legendary. Probably.”