How do you defeat Jack of Blades?

Ok, to defeat Jack of Blades. First of all you need to kill the guys around him to get to Jack. Then, attack him with your arrows and if you feel brave use your sword. I highly recomend slow time, heal life and lightning for the spells to have on hand.

Then when he starts floating use lightning as much as you can. It would probasbly be a good idea to put your mana potions on a hot key so you don't have to stop. Good luck!

This is what I found works very well:

Start by killing his minions (your choice on method)
then once he starts flying back and forth, lock on with your lightening once he is in the middle of the room flooting, stand directly below him and use enflame as fast as you can (you are invincable for the second that you are performing the spell, he can only hit you while you're refilling your mana).

It takes about 3 refills of mana with level 4 enflame to finish him off and actually, the same thing goes for rock trolls, I found if you stand next to them and smack them with your sword, then use enflame every time they try to slam down on you, you can beat them easily without a scratch.

Alright, all you have to do is have multi-arrow and berserk, I recomend at least level three on both of them, kill all of the guys around him then go to Jack. Use berserk and just hit him with your sword. When he starts floating hide behind the big rocks that pop up and finish him off with your bow using multi-arrow.As simple as that!

I use slow time and multistrike until he takes to the air, then I cast lightning at him until he's dead. I have will potions set up on a hotkey so that my magic power never runs out. He can't attack while he is being hit by lightning.