My question is what should the treasure be? I don't want it to be just simply
gold and magic items I want something epic!!!
Wishes. Something to do with Wishes. That way, everybody gets what they want, and it's a treasure worthy of the gods.
The Urn of Nine Wishes. It contains the ashes of the dead god of magic. Sprinkle a handful and gain a Wish.
The Orb of Unlimited Wishes (but only one per person).
The Book of Wishes, where a page disappears each time a Wish is granted, and there are only so many Wishes left. In the beginning, the gods wrote this book and created the world with it. Along the eons of its existence, different mages and scholars have come into contact with it and used some of the pages. Now, only a few are left. The Cult protects it. It's so secret that the Cult doesn't even know what they are protecting (lest their hearts turn greedy). There are only X amount of pages left.
The Book of Worthy Wishes, which is the same as above except that the gods themselves are bound together, by the power of the relic, to make the Wish come true. But, all gods, good and evil, must agree that the Wish is "Worthy", or the person asking blows up into a big ball of fire on the spot.
Players always love mysterious, powerful relics, especially if the relic can let them grow their character in a way no other magic item can. And, the Wish is powerful enough to be something that every king and every religion would hunt through the ages. It's powerful enough to have its own protecting cult.
That's what I'd do, anyway. Something like that.