Just got my Prime mode completed and I figured I'd provide some info and answers that I myself was curious of up until this point but could not find anywhere online. Prime mode does not unlock Zeta Prime or Dead End, nor does completing all off the achievements, it also does not add "Prime" to your name or any of your classes. I'm sure of this because I'm at 1000/1000 gamer score for the game. When you select the option from the menu it warns you that you'll loose all of your gained exp and will be rewarded with an emblem. It does just that and nothing more, it resets all of your challenges and adds a new tab for "Prime Mode" challenges. I've compiled a list of all the challenges if anyone was curious: They are simply for activating each kill streak a certain number of times in a match or just using them a total number of times. (Except for the first one) Not really that special, they DO share EXP between classes, I earned 8,000 worth of challenges playing as my Soldier and I got 8,000 for every one of my characters. I hadn't touched my Scout, Leader or Scientist and they leveled to 5 instantly. They still use the same 3 tiered system, the ones posted are simply level one. I currently have to get three Omega Missiles, 4 EMP things or 5 Ammo Beacons in one game. x__x That's it, there you have it, Prime mode ladies and gentlemen.