When leveling your soulforge, you need to be cognizant of how many battles you have fought. You are not credited for additional kills. If you need 60 kills to get to the next level, the game only saves 60 kills. If you are thinking “I’ll just do PvP for an hour and then get a bunch of soulforge levels”–nope. You can get the next level and then you start at zero again.
I just wasted a couple hours thinking those very mistaken thoughts.