The "Defeat Rhendak the Crazed" event in Diessa Plateau does not give proper rewards when completed. It's supposed to spawn another chest on the ground, other than the one Rhendak comes out of, once Rhendak is defeated, even when only doing it once a day. This extra chest rarely appear. Speaking of chests, actually, the same can be said for the Flame Legion Fire Shaman in Iron marches. That chest rarely appears either.