Draconis is a tough bastard,
. I did watchers keep right after leaving Saradush, so I had some higher level skills. Basically I spread out, lower his magic resist, while my warriors and summoned creatures attacked him. Then pommelled him with my most devastating magic attacks. Hint: the bastard doesn't like fire. Dragon's breath worked great against him. Mind you I used a heck of alot of healing potions and magics, I lost a couple NPC, I got bloodied, but in the end the overgrown rat bastard fell. Ya baby...