Solo Cavalier vs. Improved Illasera

[estaze]

I was really looking for a rumble when i started out SoA, with Ascension, Tactics i.e, though i hacked my way pretty easy through SoA. And now i'm comletely stuck with Improved Illasera. Im level 27 Cavalier with some good items, and good stats, but still i feel like i don't stand a chance against her.
I've tried summoning devas, skeletons, djinnies, but nothing seems to do. At the beginning of the battle she casts Hardiness, and is only taking about 5 damage from my hits. And her arrows really hurts..... The spellcasters shouldn't be a problem since i have 80% MR and cloak of mirroring.

Is there no way that you can beat her without a full party? I just don't feel like starting over again, just because of her. I've heard about a Shield that reflects missiles, but i dont have it, so that is not an option. If you have some good information on how to kill her, please tell me

[estaze]

Actually i think i've found a way to beat her. First i summoned 3 skeleton Warriors and then a Deva. Casted defensive stance on them and walked out of enemies sight. The Deva now showed its real value, and actually did some damage to her, and survived very long. Then i walked into the battle again, and by that time, her Hardiness and Called shot (or whatever it is) had disappeared. But i was alone against the mage, illasera, the priest, and the 2 skeletons who were charmed. I got her down on injured, which isn't very lethal, but still, if i could be alone vs. her, i could probably beat her.