DeathXmon (Event Pack 7) #BT9-112

When you would play this card, reduce its memory cost by 3 for each Digimon and Tamer your opponent has in play.
[On Play][When Digivolving][De-Digivolve 1] all of your opponent’s Digimon. Then, delete all of your opponent’s level 4 or lower Digimon.
[End of Opponent’s Turn][Once Per Turn] Delete all of your opponent's Digimon with the lowest play cost.