What's next?

Go to the Arena.

You and your sister flew off towards the source of the massive gathering of mortals. You flew above it, it was some sort of arena alright, but it was guarded by humans dressed in military fatigues and holding weapons. Your sister's tail thrust in and out of your pussy as you watched them, you could sense the holy power coming from their weapons as they ushered mortals into the arena.

Your breasts heaved as you flew around, these mortals wouldn't make it easy to get in. You moaned as you came hard, your juices falling down to the ground below, maybe if you were lucky that would infect some of these mortals. As the two of you landed on the roof, your sister pounced on you and began eating out your pussy while you thrust your cock tail into her, your mind wandered.

Looking around the roof you could probably find a way down inside the arena if you wanted.

You could also sense mortals on the fringes of the area. Probably they were either on a patrol or something to keep you out... how foolish.

Finally you could sense mortals on their way to the arena, perhaps you could intercept them before they arrived.