Something I just started doing on the mounted phase, I have the tank get close and agro, but then I back up to my team near the wall. I try to keep all the mobs close so they can't breaker or charge. It helps me a lot to avoid that first burst where I always had to swap horses on the tank very quickly. Of course you get the burst when the mobs all gain distance and drop your shields, but you do gain that first round of damage with out losing a horse and time. Hope this helps.