It’s going to be LEGEN -wait for it- DARY!
The Legendary Rank system gives level 50 players six new passive skills, each passive has two influencing factors, the strength and proc chance. Proc chance has a limit, but some power levels have no upper limit meaning your potential power level is over 9000!
The Legendary Rank system will be a part of the next update for Warhammer: Chaosbane.