Make sure you are feeding to get your vampirism to stage 1 so you don't take flame damage because most vet dungeons have a ton of flame damage. Put all your attribute points into magicka. i would do an even split between thaumaturge and elemental expert and sprinkle just a few points into penetration and crit until you get more champ points because these are what increases your damage the most.

Skill wise: inner light, force pulse/crushing shock, liquid lightning, crystal frag, bound aegis on destro bar making sure to medium attack weave; empowered ward, harness or dampen magicka, boundless storm, power surge, bound aegis. I only would use resto staff to restore magic. You shield up and do damage with power surge to heal so this is why using a resto skill is not necessary. Ultimate OVERLOAD!! This ulti is why sorcs have such great dps in dungeons!!!

Also, gear wise, 5 piece julianos with max magicka glyphs, 2 piece kena, 3 arcane willpower jewelry. any flame staff will do until you get maelstrom staff just make sure it is sharpened or nirnhoned. Make your flame staff gold first!!! Then worry about increasing your armor to gold. Get spell damage glyphs for your willpower set. Use all light armor with 2 infused traits on the shirt and legs and the rest devines or you can go all devines since these will give you the most benefits to your dps.

I know it is a lot but I hope this helps! I personally use 2 nirnhoned torugs pact swords in place of the resto because it increases my damage while using overload.

These are all things I wish I knew sooner than I did and I am fortunate to have great guildmates that have helped me a ton. If you are on xb1 na aldmeri dominion send me a friend request and I could discuss this further.