Perhaps this may be considered the coward's way to win this battle but it worked like a charm for me....
Around the sides of the temple is an area shaped like a cone where you can tuck the party in and only one enemy can attack you (physically) at a time. So I ran in and initiated battle and then ran around the side. In between I cast soul shield (I always walk around with magic screen and armourplate) and take a potion or two for added help.
Eventually the Death Lords come out and I kill them one at a time. Then the elementals. Then battle stops. After a little rest or heal I run in and take out the mages. Did it first time!!
Around level 16 mind you...