I want to buy this game for my friend and I to play. I wanted to know if combining the two order forces and two destruction forces is legal, but also a good way to play, does it add more fun or is it just a pain to pay for all those resousecs you dont have because you have two factions on your deck

Sometimes the addition of another race helps your deck by shoring up any weaknesses or augmenting any strengths. The addition of the alliance cards helps to alleviate the loyalty costs somewhat.