A very Short Commentary on Tobirama's so-called "OP Jutsus"
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Tobirama's a scientist because he invented Edo Tensai by studying human bodies. Orochimaru cited him as his sole inspiration in his human experimentation endeavours. (You know how Edo Tensai works? It requires a live sacrifice; I wonder how many people this man must have experimented on, tortured, and butchered before he ever invented ET as Jutsus aren't created overnight; they take years to be created, let alone perfected for use; and we know this through Orochimaru's perfection of Tobirama's own Jutsu, ET, for a fact!) What "most OP jutsus in canon" are we talking about here? Shadow Clones? A dunderhead like Naruto learnt it in a few hours, and it's worthless for most Shinobi as it requires a chakra volume and stability almost all the ninjas don't have. (Who's even used it outside Leaf? I recall one mention of it in the Third War, but it's probably a mistranslation; it's a Kinjutsu because it poses a danger on the user's well-being, not because it's "OP".) Its main use also isn't combat, but intelligence gathering (remember how Kakashi taught Naruto to cancel his clone and gather together what the clone had learnt? I'm glad I'm jogging everyone's memory here). This is outright mentioned in the manga. Naruto uses it the way he does as Kurama's chakra has been leaking into his system since birth, and that allows for the mass-clones and their stability. Really, I can name at least 30 OP Jutsus right now that Tobirama never invented. (Let alone "most OP Jutsus" in canon.) Heck, never even encountered. Which "most OP Jutsus" are those, then?
The paper-tag explosives? It can't be used without an Edo-Tensai body (Tobirama used it on himself as he possessed an ET body; this Jutsu literally can't work without an ET body at your disposal); and his Edo Tensai was abysmal to the point that Orochimaru and Kabuto both took it to a level that Tobirama had to praise Orochimaru for it. Hashirama praised him, too. So Tobirama's ET isn't really OP as the ETs that were brought back using his version were at a mere fraction of their original power; and ETs can be sealed fairly easily if they're average or weak; they just have to be subdued. (S-rank doesn't mean super-dooper Jutsu; it simply means a "Secret" Jutsu; and that's got little to do with its learning curve or power.)
That just leaves Flying Thunder God Jutsu, and that I can give you; but its variant was invented by Minato, not him. So beyond that one Jutsu and some fucking pathetic Suiton Jutsus, which accomplished jack-shit in war, which OP Jutsus am I missing? Some of you really need to read the manga in lieu of making fanons in your heads.
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EN: This will be added to Tobirama's chapter to avoid any confusion on his "OP" status.