The Monarchs Stormforth (SR01-EN027) [Structure Deck: Emperor of Darkness]

Once during this turn, if you would Tribute a monster(s) for a Tribute Summon, you can Tribute 1 monster your opponent controls as if you controlled it. You can only activate 1 "The Monarchs Stormforth" per turn. During the turn you activate this card, you cannot Special Summon monsters from the Extra Deck.