xD I just can't beat him, any tips ??!?!

Build up a nice and hefty tank with enough elixirs to keep it (and other members of your party, they're important too) alive while you're killing them.

Also, go in there with 100% mana, if you haven't done so already. xD;;

Focus all your power/finishing moves on 1st turn on one of the copies. It's random which is the real one, but just manage to finish one off so you can narrow down your choices. While you do so, work on both building up mana and staying alive on all fronts. x:

Just focus on one at a time, don't spread yourself thin, and stay alive. ;w; Good luck!