Kiting on impossible?

[Sanctuary]

Right, that's what I tried over and over again. I would move up to the point to where it would move close enough to almost hit me, then click around a fourth of an inch behind me to move and when I would move the pack would not and would then simply sit there a while and reset. The robot boss in the labyrinth seemed to be in a similar placement, but I was able to kite it out and grab the amulet without having to fight anything, and this should be the same but doesn't seem to be.