Grounding totems are complete hax. I'm overjoyed when I have a group of all casters, because it means I can just stand there looking pretty without having to actually tank, while my shammies blast them down. All the damage they deal goes into the grounding totems.

If you're worried about casters standing still and pulling nearby groups, just position your shammies far enough away, aggro them, then run back. They will try to cast, realize that you're now out of range, then run over to you.

The mind control guys are just part of the zone; you have to deal with them even when you're not multiboxing. They have very low HP, and mind control takes a few seconds to cast, so you just have to be on the lookout for the mobs called 'Phantasmal Possessor' and get some frost shocks or lightning bolts out on it as soon as it spawns.

But mostly, don't worry so much about tanking everything. If you pick up the melee mobs, and remember to keep down grounding totems, the rest of the enemies can do whatever they want; it won't hurt you.