Simple suggestion.

Rally Cry should additionally provide pull/push immunity in order to make warriors actually useful in the Ren'Gol maps for all parties. Since the mob count for the boss spawn is very low comparing to the total mob count, it's only natural that parties will want to skip some and run to the boss area. This upgrade targets exactly that.

Note that this is a skill upgrade which, unlike other popular ones who would have more impact like extending VB buffs to party, will not really cause any drastic changes in PvP and in fact would just add another option for a clash warrior. Making something like a skill upgrade not work at all in PvP (because you know what VB party buff would do for tank stacks) is much harder than changing a stun/root to a slow.