Jhin
Indeed, after the release of patch 12.1, there are numerous factors that help Jhin become a top carry in Teamfight Tactics. First is the fact that many counter compositions like Kai’Sa – Icon and Chemtech have been nerfed and are no longer as dominant. Therefore, Jhin will face fewer compositions with too many tanky champions that are both “beefy” and hard to take down. With a champion like Jhin, who has limited attack speed, it’s difficult for him to quickly eliminate champions like Sion or Galio.

Moreover, Orianna being buffed also significantly strengthens the Jhin – Guardian team in battles against meta compositions. With the maximum energy stat reduced, Orianna often casts her ability at the same time as Jhin or Miss uses their skills. Combined with Braum, this creates a long chain of crowd control along with massive damage inflicted on the enemy team, making this composition easily wipe out opponents. If you have multiple B.F. Sword, Jhin is the top choice.
Seraphine
One of the notable updates in patch 12.1 is that Morellonomicon was heavily nerfed in damage output, so Riot buffed champions that utilize this item as compensation. Seraphine is among those champions, and Riot even reduced her maximum energy by 10 points. This makes Seraphine suddenly a highly versatile damage dealer who can also heal allies while dealing massive damage.

This has even directly contributed to the resurgence of the Innovator composition to the top of the meta alongside the buffed Gadgeteen. Now, the Innovator composition has become a more resilient version of Kai’Sa – Icon, boasting tremendous damage across multiple targets, continuous healing, and no fear of lacking crowd control. The items you should aim for with Seraphine are Spear of Shojin, Archangel’s Staff, and any item that boosts spell damage.
Lux
Fairly assessed, Lux is essentially a magical damage version of Jhin, as the operational mechanics of these two champions are quite similar. Even their weakness of struggling to quickly eliminate tanky units is very much alike. Therefore, when compositions like Kai’Sa – Icon or Chemtech were relatively heavily nerfed in patch 12.1, Lux also greatly benefited and became one of the top carries.

The advantage Lux has over Jhin is that the team composition is simpler and does not require too many hot Sorcerer units. Moreover, before acquiring Lux, the Mage team also possesses several champions that deal decent damage and can hold items for Lux, so the likelihood of maintaining health in the mid-game for this composition is higher. If you start with items that provide energy (Tear of the Goddess) or skill damage (Rod of Ages), then Lux is the carry to aim for.