Hiệu ứng của Flogos, the Ogdoadic Boundless có thể được kích hoạt khi đối phương không còn các Vùng quái thú Chính không?

LIGHT 4

If this card is sent from the field to the GY, or Special Summoned from the GY: You can target 1 face-up monster your opponent controls, and 1 monster in their GY with an equal or higher ATK than that target; Special Summon that monster from the GY to their field, and if you do, send that other monster they control to the GY. If this card is in your GY: You can send 1 card from your hand to the GY; add this card to your hand. You can only use each effect of "Flogos, the Ogdoadic Boundless" once per turn.