I'd also go with Blizzard, because T-storm sucks Maybe you could substitute it with Firewall...20 Firewall + 20 Fire Mastery would be cool.
Infinity is excellent for all sorc builds and is also a very nice merc weapon, go for it!
People usually don't put any points in energy (unless they use energy shield). Because 1.10 is quite dangerous most people prefer life over mana...also Shako, Frostburns, SOJs, Silkweave, Glooms Trap, etc boost mana quite a lot so you can get by fine with no points in energy. If you feel like you're lacking mana, it's not a crime to put points in energy...alternatively use some mana charms.
On a sidenote it's going to take a long time to get that many skill points so don't expect to finish those builds anytime soon.
I just wonder if it´s a good idea to mix Fire and Ice?
My old Sorceress used Fire Wall and Frozen Orb. I´m not sure if I wanna make a new one exactly similar to that, but Fire Wall and Blizzard could be fun.
I just wonder if perhaps a Blizzard with maxed synergies could be powerful instead...
One more thing, what is the lowest resistance an enemy can have. I meen when you use Cold Mastery.
And What happens when Infinity breaks immunites with Conviction Aura? How much does it lower their resistances and how does it work together with Cold Mastery?
i myself play orb/hydra,and consider to be a good match.hydras make great watch dogs for around corners and covering your back trail.especially in the worldstone chamber when there are gloams.i can finish hell alone with no problems.
the down side is you have to be patient,this is not a fast killing machine when there are cold immunes.though a good merc helps.