The Untouchable

You have to get 0 damage at this one and if you do it you get the weakest weapon of the game which kills a bomber with 2 hits. You have 3 ways to do it, but I will tell you the easiest way. So first have a big team and play on Leipzig. Play as Chaplain class and stay in the back of the team. You have to do not deal damage with your stake to zombies and you have to use the crucifix 5 TIMES while doing Leipzig. You have to get 0 hits, do not deal damage and use 5 TIMES the crucifix and so you will get it easy. (This was my first hidden acheivment and I was able to do it on hard maps like Westminster, Saint Petersburg, London and Copenhagen.)