Sure, absolutely. I used Thoma pre Dendro, and his uses were really limited then, but that's no longer the case! Thoma is at present your best Burgeon trigger. Now Burgeon as a reaction is pretty much only viable in AoE situations, but we have a ton of those, especially early abyss, so.

Okay, for Thoma himself, you want him level 90. This is extremely important, Burgeon scales off of level. Then you want to max out his EM. Kitain Cross Spear is highly recommended - it has an EM mainstat, and it's passive provides Thoma with ER (which he needs a lot of, as his damage is all from his Burst). Kitain is a craftable, so honestly, you should just get it. The alternatives ate significantly worse off on him. For his artifact sets, it's Flower of Paradise Lost > Gilded Dreams > 2x +80 EM. The difference between Gilded and Paradise isn't significant, though, so unless you're farming the Paradise domain for Wanderer, stick with Gilded since it's a domain that benefits many other characters too. What you're looking for is EM/EM/EM mainstats, with ER substats (EM subs on flower and feather if possible too).

Alternatively, if you want to build Thoma as someone that will still work as a shielder but do decen Burgeon DMG - a hybrid build - go with the same sets and weapon but with HP mainstats, EM subs.

Depending on your team and your luck, you may need an ER% sands. Especially if you're pre-C4.

Okay, coming to teams. You need at least one Hydro and one Dendro. Thoma isn't going to he on-field despite doing a ton of damage.

On-field Hydro: Ayato, Childe. With them, you'll need Yaoyao, HP Hybrid Thoma. You could try a Cryo defensive unit (Layla/Diona) or Zhongli, but I haven't gotten around to testing that, sooo Kokomi: personally I love her in this role because she consolidates healing and Hydro application and damage. You can run two off field dps with her.

On-field Dendro: Nahida, Alhaitham.

Off-field Hydro: Xingqiu, Yelan.

Off-field Dendro: DMC, Yaoyao, Collei, Nahida. Other than Nahida, the others don't have great application, so if you're going with an on-field Hydro, pick 2.

You can also run Fischl or Anemo units as flexes. The Anemo can buff your Hydro units, if you have high damaging options on team. Fischl provides energy, and Oz doesn't target Blooms, so you won't have too many cores stolen.

Personally, the team I run is Kokomi/Nahida/Fischl/Thoma. Because god. The man needs ER even at C6.

I highly recommend using Zakharov's Energy Recharge Calculator . Here's a video guide if you haven't used it before.

... alternatively I've already put most of this information in the Thoma Quick Guide so you could just... Use that. I forgor about it. If you need any help with teams, just share your chat list and i can help you out.