Diabolos, King of the Abyss

Cannot be Special Summoned. If you Tribute Summon this card, the Tributes must be DARK. Cannot be Tributed by card effects while face-up on the field. Once per turn, during your opponent's Draw Phase, before their normal draw: Look at the top card of your opponent's Deck, and if you do, place that card on either the top or bottom of their Deck.