Scrapgorger Dragon

Flying, Trample
When Scrapgorger Dragon enters the battlefield
exile target permanent you control.
At the beginning of your end step you may pay {x} to exile target nonland permanent you don't control with mana value X or less. If you don't,
exile target permanent you control.
Scrapgorger Dragon's power and toughness are
equal to the total mana value of the cards exiled
with it.