As a mage, I found this fight to be buggy as heck. If you use all your cooldowns at the start then he seems to just run around after you without doing any of his other things. So DPS him (don't use your Mirror Images) until he makes up his mind what he is going to do: charge or wander around.
If he charges, wait until he is casting his special ability and then Blink behind him. Now use your cooldowns.
If he does special ability, just DPS him until he charges and starts casting his attack, then get behind him and activate your cooldowns.
Remember, don't try to run away until he starts casting his special attack. It varies on whether you sit and wait or move right away.
As a mage, I found this fight to be buggy as heck. If you use all your cooldowns at the start then he seems to just run around after you without doing any of his other things. So DPS him (don't use your Mirror Images) until he makes up his mind what he is going to do: charge or wander around.
Remember, don't try to run away until he starts casting his special attack. It varies on whether you sit and wait or move right away.
For a better write-up read Ozlem's comment on Wowhead.