I was playing solo on the Winter Kell mission at a pretty low level for the Queen's Kill Order, and kept dying on Draksis, and then I figured out a really easy way to kill him. 1: Keep behind the entrance and take a few shots at Draksis. The door shuts behind you, so never enter the room. Draksis will take cover and stay there until you step in (he always stood in the exact spot to the right of his throne for me). Staying behind the doorway also keeps reinforcements from spawning. 2: Kill the Dregs/guards. 3: Throw a grenade towards Draksis. Mine didn't even get close to hitting him, but he immediately jumped out of his cover and started running at me. 4: Kill Draksis using the stairs leading up to the room as cover. He can't leave the room, and most of his shots miss because of the awkward angle between him and you at the bottom of the stairs. Hope this helps.