Diabolos, King of the Abyss (FOTB-EN061) - Force of the Breaker Unlimited Number_DL13-EN019 You can only activate this

You can only activate this effect during your opponent''s Battle Phase

but they cannot activate their Pendulum Effects this turn

negate the activation

Card TextFlip all face-down Monster Cards on the field face-up (Flip Effects are not activated)

9 cards per pack:

Diabolos, King of the Abyss (FOTB-EN061) - Force of the Breaker Unlimited Number_DL13-EN019 You can only activate thisTypeDragon Effect Monster AttributeDARK Level Rank7 ATK DEF2800 1000 Card TextThis card cannot be Special Summoned. If you Tribute Summon this card, the Tributes must be DARK. This card cannot be Tributed by a card's effect. During your opponent's Draw Phase, before their draw, look at the top card of their Deck, then put that card on the top or the bottom of their Deck.