Pre 2.1 Bards may fire RoD during a big pull or in situations the tank has to take many mobs like T4 to help tank in taking less damage

In 2.1, RoD has been nerfed to become pretty useless, so like what Peptaru said, Bards only use Wide Volley as AoE, if it results in RoD as a free proc, then hooray and use the free proc, and if you got that lucky to trigger a QN free proc, then hooray again