How to rank up fast in survival mode

[ArmorDonio]

While i was making a video about hatred, i discovered a handy spot where enemy's could only get from 1 side and you can shoot them from afar with an rifle but i sadly died because i forgot to look at my health.



https://www.youtube.com/watch?v=9wD64lXDcA8
around 5:48 in the video

[Lord Tony]

In the federal building if you shoot a hole in the bathroom the enemies won't bother you at all up until the rocket launcher men start coming.