Dark Death Ball

If you have a green Unison Card in play : If the Battle Card being played has an energy cost of 4 or less, it's placed in its owner's Drop Area instead of being played, then choose up to 1 of your opponent's Battle Cards with an energy cost of 1 and KO it.
If all of your energy is mono-green, you can activate this card's skill from your hand without paying its energy cost by choosing 2 other cards in your hand and discarding them.