Mike, The Zapper

This spell costs {x} less to cast, where X is the number of creatures you control.

When The Zapper enters or attacks, exile cards from the top of your library until you exile a creature card. You may cast it without paying its mana cost. For each card exiled this way, The Zapper deals that much damage to target creature you don't control. Put the exiled cards on the bottom in a random order.

The Zapper's power is equal to the number of cards put on the bottom of your library this turn.