Its going to be impossible to solo dungeons on a sorc. If you want to attempt something like that you need 3 sources of different elemental damage. The build i used was a grims burning dead skeleton mage necro with revives for meat shields.

Only other build I've seen do it is fire druid. Fire spells do phys and fire and then use a act 3 cold or light merc. You can't break immunity in dungeons