Thau got buffed heavily with some of the more recent patches. With ThauC3, maxed attributes and full SPR build, you gain about 2.5k magic attack from buffs (closer to maybe 1k before) which is also shared with your entire party. The INT from Swell Brain also boosts your summon damage a little (as it still scales off INT+SPR, even if SPR gives more now). The main draw of Thau/Sorc build, though, is that you can put everything into SPR to maximize summon damage without losing too much of your own damage. Your summon acts as a steady stream of DPS and a distraction to keep monster aggro off you, and from there you can concentrate on buffing/debuffing and using your other skills to deal additional damage.
It’s more of a supportive/party-oriented build IMO, so you won’t be dealing super insane damage on your own, but it’s an effective build for casual solo play as well as grinding in a party.
Sorc/Warlock always sounded like a fun combo to me… I’d say go for it. Sorc2 is all you need for Sorc right now since C3 is really meh, so you could go Wiz1/Pyro or Cryo3/Sorc2/Warlock2. I see lots of Cryo/Sorc since you can use Frost Pillar to draw in large groups of mobs for your summon to attack.
Also…
There’s more discussion on this in the Sorcerer Megathread, but summons are still being tweaked and Strike-AA summons are looking more appealing lately. Helgacircle/Mirtis/Rexipher seem to be on par with TS in various ways from what I’ve heard? Hopefully in the future more rebalances will be given to card summons to make them more equal in strength vs TS being the only decent card that’s easy to get a hold of.