HS entrance solo (shm)

[DrKvothe]

56 shaman, just began soloing HS entrance. It was a bit of a shit show at first, but then I figured I had it down. 4 mobs at a time, 3min root + 2 epic dots, repeat once, loot.

But after about 10% exp, a caster skeleton barged into the room and forced me to gate with a bunch of dots on me. He broke root quickly, and the dots did a lot of damage. I doubt I could solo him. Any tips on how to avoid this guy?