I'm usually at twice the threat of my shammies or more at that point in the fight, so unless there's some effect that Omen isn't aware of, my pally is still the tank. And I always have aggro when I use the lame-o mushroom trick, so I don't think that's the problem. When I tried using dispel, I cast it about four times before giving up; the levitate debuff seemed to just pulse back on immediately. I was getting to the ground a little bit faster, but he'd already gobbled down one shammy and was working on a second by that point.

Using the mushroom makes the fight an easy tank-n-spank, but I hate tricks like that

Fear bombs are no problem with shammy power