Stonecore
- The final boss.. you have to do about eight things here all at once
Dead Mines... impossible as a multiboxer.
- Good luck avoiding the rotating fire on the first boss and maintaining high amount of AOE dps on the adds while nuking the boss

These have all been multi-boxed. Farm the easy ones get your gear up or wait for nerfs I guess. Try pvp, but if you aren't having fun find something else. It happens maybe try 1 toon and see if you enjoy wow at all in different aspects.