I got 28 mins in survival and quit being tired of it. My spells were as follow: earthquake, reaper, locust, mana pot, polymorph and curse. A great combo is earthquake + polymorph as only the toughest guys get a sheep in their butthole.
A few hints: as soon as you start seeing Ice Knights, cold resist gets really important. They really are the only real threat. I had a vampiric reaper. The critical hit really helps draining hp. My stat placement was 1.3/1.3/1.3/0 You do that by spending 2/1/1 for one lvl, the 1/2/1 then 1/1/2. When stats reach around 100-120 go full strenght. The cold resist is all that saved me. Only spells used were critical and shield. At lvl78, it's getting hard to get killed.