I need a bit of advice on sorc build

I would suggest not doing light fire sorc. Use orb is very good and doesn't require alot of mana. Then if you want to use fire use meteor and fire mastery and some in warmth, just static them and run around them until meteor comes down. I on the other hand use nova,ts,lightmastery on my sorc, with static to bring down their life. But use orb, its easy and does enough damage, and won't drain your mana like cb will if you don't have enough mana.