Storm Kombinen

As you cast this card, you may discard any number of cards from your hand with the subtype "Kombinen" and pay {2}{w}{u}{g}. If you do, return all non-land permanents your opponents control to their owner's hands with converted mana cost
X+2 or less, where X is the number of cards discarded in this way. If you don't, all creatures get -0/-1 until end of turn.