[2020] Please allow playing Heart of the Fluft when the resulting board would not go over 6 units

My poro deck still isn't gonna beat you guys, but at least this removes its most irritating flaw.

If anyone would like to argue otherwise, I will point out that you can have 7+ units mid-combat (i.e. when leveled Braum survives damage and creates a poro), but the game lets you keep all of the resulting units. Consistency please.