Tengen is extremely powerful in a support and “world‑scale” way, but is not a front-line fighter like Gojo or Sukuna.

Who Tengen Is

  • Tengen is an immortal jujutsu sorcerer whose body evolved into something closer to a cursed spirit after failing to merge with the Star Plasma Vessel in 2006.
  • Their existence is fused with the world itself, making them more like a consciousness that governs barriers and cursed energy than a conventional human sorcerer.

Core Powers and Hax

  • Immortality & evolution: Tengen does not die from natural causes and has lived for over a thousand years, gaining immense knowledge and refined techniques in that time.
  • Barrier mastery: Multiple sources describe Tengen as the most skilled barrier user in history, capable of creating and maintaining large‑scale structures like Curtains, Pure Barriers, and even Domain‑like expansions across Japan.
  • Spatial manipulation: Tengen can distort space, connect distant locations, and hide special‑grade cursed objects in a multidimensional “storeroom,” making it almost impossible to pinpoint their true location.

How Strong Is Tengen, Really?

  • In combat , Tengen is explicitly noted as “not a great combatant,” so they are not meant to trade blows with monsters like Sukuna or Gojo.
  • In support and influence , Tengen is absurdly strong: their barriers shape how jujutsu society functions, concentrate cursed energy across Japan, and boost sorcerers’ techniques nationwide.
  • Their intellect and foresight let them strategize against top‑tier threats (e.g., planning around Kenjaku with Yuki and Choso), giving them “commander” level value rather than “duelist” strength.

Limitations and Feats

  • Tengen’s barriers can be bypassed or exploited by exceptional cases like Toji Fushiguro, whose lack of cursed energy lets him slip through detection, showing that their protection is powerful but not absolute.
  • Their evolving, near‑cursed‑spirit nature means they can become a huge liability if someone like Kenjaku merges them with humanity, which is why antagonists target Tengen as a world‑level resource.

Simple Power Verdict

  • As a fighter: probably below top‑tiers like Gojo, Sukuna, or full combat specialists, since Tengen is not portrayed as someone who actually brawls.
  • As a system‑level entity: one of the most important and overpowered figures in the series in terms of barriers, information, and control over cursed energy, arguably “stronger than everyone” in that specific niche.

TL;DR : Tengen is “broken” as a barrier and support sorcerer who affects the entire country, but is not a 1v1 monster; they are a strategic, world‑tier piece on the board rather than a frontline fighter.