Well, first of a the surgeon is way better than all the other epics you will get(Aside from deadshot). The surgeon is a very powerful unit, and its easy to get her past 10,30, and 50, if you have enough crates. The power in units comes from what teir they are va what rarity. (Example firefighter is first tier, fire cheif is second, and fire marshal is third). I have tested all the campaign units, and the surgeon is tied for best along with dead shot. Trust me, its worth it. Also, the main attraction to the game is finishing campaign and joining an active guild that's almost constantly raiding. The people and gameplay are fun. The whole campaign is more of one great big tutorial.