If you control a monster, you cannot Pendulum Summon. This effect cannot be negated. Once per turn, if a Synchro Monster you control destroys an opponent's monster by battle and sends it to the GY: You can Tribute that Synchro Monster you control; Special Summon that monster to your field.
[ Fiend / Synchro / Pendulum / Effect ] (This card's original Level is always treated as 12.) Cannot be Synchro Summoned. Must be Special Summoned (from your Extra Deck) by sending 2 Level 5 or higher monsters you control with the same Level to the GY (1 Synchro Monster and 1 Pendulum Monster). If this card is Special Summoned: Destroy all cards on the field, then inflict 300 damage to your opponent for each card destroyed this way. If this card in the Monster Zone is destroyed: You can place this card in your Pendulum Zone.ATK / 0 DEF / 0