HoR is actually just fairly tricky in general. You have to use all the tools you have: spell reflect, taunt, heroic throw, LoSing around corners to try and get them to the same spot, etc. Also due to hit box issues a lot of shockwaving then stepping back to get positioning is pretty important. Lots of cleave/tclap/spellreflect and your party focus firing should help out a lot. Charge, Intercept, and Intervene are also very powerful here.