Idea: 1 card is always in hand at the start of the match.
call it ”ideal slot”, I.e. you always have a win-con or building to choose from as a card that’s in your hand… can’t have it evo’ed or hero or champion in the slot however.
[Ideal Slot] [Evo Slot] [Evo/Hero Slot] [Hero Slot]
Exception: Pump and Mirror can’t be in the Ideal Slot.