I usually walk until I notice an aggro ! that shows up in a seemingly empty square(or if my output shows ALERT! WARLOCK! due to their visibility). Once that happens, I spam #20 kick warlock until it connects, then recall. Once that's done, I walk a little bit back towards Raash, ambush the warlock, and then recall one last time so that it's determined to come to the temple, where I ambush it one last time so everyone can see and join in.
Yeah, I'm an ambush addict.