Well here’s atleast how it works for me (and should for you guys as well, I guess): I complete dungeons and when I’ve collected 7 stars from them (if you finish 3 dungeons, all with 3 stars, you won’t get 9 together, 7 is maximum you can hold at once) I can watch an ad (for free) and get some prizes after the ad (gold, keys, ingredients, potions).
Plus I really really really really really really really (add more stress here) want a “close” button on the GXP upgrades. I don’t want to spend my orbs on this element of the game and can’t pass them up, which I feel is total garbage. Why should I have to spend my highly valued orbs in order to see another “rare option” in the GXP level up screen? I want to skip it and help up my guild faster (this would also be great when, say, u are out of stupid powder and have to wait like 10 ritual runs to get enough to use the “rare option” and open up other rare options).