This has been brought up before somewhere deep in one of the armor bonus threads, but I figured it's worth repeating for quality of gameplay purposes.
On the latest "close-to-final" Bullroarer build, it's (still) possible to get a 0, yes zero second cooldown Rallying Cry with the new changes to set bonuses.
In the screenshot below, I've equipped 2x pieces of the 65 Helegrod armor and 4x pieces of the 85 PvMP Perseverence set. From my understanding it works with any sets with the defeat event cooldown. The bonuses stack. I have the emblem legacy also.
Rallying Cry with no cooldown:
Now, this could still change before U10 hits live, but if it doesn't..prepare for the Rallying Cry spam?