Crystals are the currency sold for real money. These buy the same loot crates as Credits do - i.e. which primarily contain a few randomly-chosen Star Cards. In theory buying Crystals enables you to sidestep the lengthy play matches - earn Credits - buy Crates - get Scrap - build/upgrade Cards loop - but, if you're after specific cards, the blind bag element means you'll almost certainly have to buy multiple Crates. Crystals also can't directly buy Credits or Scrap, but you're very likely to find some by opening a few crates. Crystals cost: