I play a Mage and I've noticed that, if I Polymorph a player that is mounted, they get dismounted. However, I've also noticed that it doesn't work for players that are not on the ground.
Are there any other abilities that dismount enemy players? And is there any way to dismount a flying player?
Dismounting flying players is no longer possible, flying targets are immune to all forms of CC. Also for a mage another certain way of dismounting is not known to me. And according to Daze a player induced daze doesn't dismount a player from his mount. So all in all, Polymorph is your only way of forcing a dismount of a player.
According to this Source dismounting other players on flying mounts will be possible again in Mists of Pandaria. But I don't have any further link to back this up.
The Mists of Pandaria expansion released the Hardened Shell item, dropped by the rare NPC Nessos the Oracle in Kun-Lai Summit. This item has a 0.5 second cast time, a 40 yard range, and can dismount a flying player as long as they can be attacked (i.e. both hostile and PvP-flagged). It does not provide the victim with any sort of safety mechanism (eg. a parachute), which allows them to potentially die from the fall if they are dismounted from high enough. It also works on a Druid's Flight Form.
The Hardened Shell is currently the only way to dismount a flying player or to force a druid out of their travel forms.
The only other means of dismounting a player is with a Polymorph effect, namely the Mage's Polymorph and the Shaman's Hex. To clarify, these do not work on flying players or shapeshifted Druids.
