More fun with Dead Reckoning

Imprint — , : You may exile an instant or sorcery card with mana value X from your hand. At the beginning of your upkeep, you may copy a card exiled with this artifact. If you do, you may cast the copy without paying its mana cost.

Trample When this creature enters, sacrifice it unless you sacrifice any number of creatures with total power 12 or greater.

You may put target creature card from your graveyard on top of your library. If you do, Dead Reckoning deals damage equal to that card's power to target creature.