I went to do the battle as a level 50 Sage. I attempted several times with Qyzen and, though it never worked, I have a feeling it could have. In my final attempt, I used Theran Cedrax. Before this attempt I had read this forum and looked for advice on how to avoid the one hit kill cave move. If you can avoid that move, the battle becomes fairly simple. I put Cedrax in his Medwatch stance and i fought him using Project, Force in Balance, Force Wave, Force Speed, and Force Armor. I stunned Syo everytime he attempted to use his Project-like ability and Cedrax stunned him occasionally as well. My advice to anyone attempting this mission, stay near the entrance: everytime he attempted to bring the cave in on me and I ran there, he just stopped his cast and I could continue dealing damage.
Happy hunting