Command the Chaff 
Instant
Look at target opponent's sideboard. You may cast a card from that sideboard without paying its mana cost. Exile Command the Chaff.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyNOT LEGALvintageNOT LEGALcommanderNOT LEGAL