In halo 3 the only spartan armour I’m missing is the rogue helmet and was wanting to try and get it after all this time. I know you need the Spartan officer achievement which includes becoming a lieutenant for an overall level, but looking online I could never get a consistent answer on how much EXP you need in a specific playlist and if you can do it in social (social slayer I have 40 EXP which is closest)