Gasmasks are the Number one key

I found out how to get the sould crystle 1. go to the crashed subway and stand in the middle of the marking sideways "left" and log out then back in you should clipp through the wall 2. next got to the crystle and place a horde becon on top of it kill all the zombies coming from the wall you came from 3. after killing them you should be teleported to the secert room from there go down in to the basement hit or go near the crystle and you get the accevment |befor you touch the crystle be noted that you will be teleport back to the real world|
I hope this work for you guys if so tell me in the comments also sorry for spelling xD bye see you guys next time.