Okay, just a few things to keep in mind when fighting her.

Keep back to the far wall to reduce the knock-back disruption.  It really is inconvenient when she knocks folks (like the healer or main tank) off the waterfall.

Use nature resist potions and hunter nature protection aura....her 'fart' attack is nature based.

I beleive she is stunnable, but highly resistant, so do not count on rogue stun-lock to save you.

Spread out....keep non-melee at maximum range.

I beleive most of the pvp trinkets gained at rank 2 will be effective against her fear.....or at least as effective as any other fear effect.

Horde: if a shaman is along, have them drop nature resist totem (stacks with hunter aura I believe) and or tremor totem (dispells fear within 20 yards on a 2 second pulse) as fits the situation for the group.  Not sure if both can be dropped at the same time; I do not beleive so.  Often I have seen nature resist totem started with, and then the shaman (at range) switches quickly to tremor when the fear area of effect hits, then back to nature resist.

If Forsaken melee is available (especially warrior) use Will of the Forsaken to keep her from running roughshod all over the rest of the group.

Alliance: if a paladin is along, they should be ready to bubble-up the healer(s) if main aggro is lost.  Getting her attention with hammer of justice will also keep her off the rest of the party.  If you go in with righteous fury up and spamm consecrate/seal of righteousness, it will help keep her focused on you....a few sunders should give the main tank the most hate from her, but if he loses it, you are a close second.  If you are the tank, this will help keep her in your face (poor you).

"She stops moving whilst farting"

Your wording make me lol.

They weren't being serious you idiot.