It seems as though its possible to obtain higher star Gods from higher levels in mystic cave. These gods are exponentially better than single star gods and provide very large boosts to your army as well as economy. However you will need to be able to clear mystic cave level 7 for a 2 star god and level 9 for a 3 star. The only way to obtain a 4 star god is by using pearls. Because of this I recommend using your pearls on getting the 4 star god. You can always find the second deed in a chest and it seems you can obtain a second city with artifacts that you get from Misty Cave. More on this when I find out though.