Tested after 1.11...
You know. Odd grps go left, even grps go right. Each side has this spot.
Well at wall, closer to spot where onyxia is being tanked, you will find that mountain (or wall or rocks or watever) that has spot where its not high. Over there stand near it (it looks a little bit, like corner), facing whelp caves and jump on the wall. Now u cannot be feared down and be damaged by fire in floor at phase 3. It is prefered to be used by those who dont do dps while tank gets agro. If you overagro on that spot, onyxia will get avoid buff which will wipe all grp. Also it does teleports you off up there to onyxia sometimes, but u can get back any time u want.