I got this achievement, the people who don't rank subway as the hardest map are insane, that was tougher than petrified shiat for me. If I wasn't getting shot to death in the very first room, I'd instantly die from a magic nade the computer would hurl from across the map into the room I was hiding in.
arena is secretly easy. If you investigate the fountain in the center, you can jump up one of its corners and the fountain top gives the perfect vantage point to see all the enemies spawning. You can kill them in 1 shot as long as they haven't jumped off the building yet.
surprising to see people complain about elevator. That one was easier for me. Well, excepting the final floor. When you get there, as long as you pick off the one shotgunner to the left (I think? Its been awhile), you can crouch behind that plant/barrier thing and take your time with the heavy armor. When he's clear, you've got to haul arse all the way to the back of the room, up the stairs, and hide in a corner before the elevators lining the side of the room start pooping out a bunch of foot soldiers.
gamer tag: Archer Spense
no random friend requests accepted.