Ancient Gear Reactor Dragon

As an additional cost to cast this spell, you may sacrifice an artifact creature. This spell costs {x} less
where X is the mana value of that creature.

Flying, indestructible, trample

At the beginning of your end step, if Ancient Gear Reactor Dragon attacked this turn, you may destroy target nonland permanent.
If Ancient Gear Reactor Dragon is attacking, your opponent can't cast spells.