Here is what you need to do.

1. you must be mage on 24 lvl
2. unlearn all your talents and spend them in arcane tree, you want arcane exploison cast instant
3. find 1 druid or priest (healer) that will be able to follow you and heal you
BUT DON'T BE IN GROUP
4. you should run into camps and crowds of mobs and start casting arcane explosion
5. after few casts, healer should heal you, and you spam arcane explosion, press that button 100 times
6. when you're done, collect the loot, replenish your health and mana and start again