mobile

Ive been out of the rooting game for a while, i have a galaxy s5 on ob1. I hate lollipop lol, too many fc. So ive decided to downgrade back to nk2. I was wondering if anyone can please let me know if I flash nk2 through odin, will this trip knox? I have no experience with knox and im not sure what it is. So sorry if that seems like a stupid question lol. Also for those on nk2 is there a way to root and add twrp without tripping knox? Thanks in advance for any advice you can give me.