Im not sure what element you use but i have a great one that worked for me in one try
Warning this works for Fire Ele only
Skill Bar, nothing more, nothing less
How to use: Easy, the second you get in there use Pacifism to stop him from attacking with axe and bow and will keep him in one place so your AOE attacks can do their work, run around because he will use meteor shower and firestorm (how ever if you feel you can fit it in before feel free to try), after he has done casting both cast meteor shower right away, then firestorm, once you do that there is nothing left to do but spam the flare like a madman and hope for the best (note: you may have to cast Pacifism more than once depending on your luck.) Using this i beat him in about 30-40 seconds. The healing is just to make sure you stay alive, you can take it out if you want to prevent your mirror from healing and thus screwing the plan, but due to constant knockdown it may or may not be a factor (i brought it because i had no idea how Pacifism would work.)
However if you are of another element i can not help you because i have no lighting skills.. but i would guess it would be pretty much the same Pacifism mixed with spell spaming.
Hope this little guide helps.
