Diabolos, King of the Abyss

Card effect (current official text)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.