what i do is rot/root on closest to wall on right. then i pull PH where last one just died. It singles for my 65 necro. then i just pull next and finish off room. when all is dead i pull the roamer which would make it easyier to kill next round of gobs etc. good luck
As a beastlord I kill the roamer first. Then sick pet on the mob on the right and stand next to the wall while fighting him. Then next you can pull named/ph to that wall. After that you can sit outside the little cove and wait for the roamer to pop again in front of the named/ph spawn point.