I, the Firstborn of God, in Warhammer 30K

In terms of technology, the Protoss could easily crush the Empire in Warhammer. If you were to write about the Protoss in the Warhammer universe, given your track record, you'd likely end up pleasing neither side.

The entire Warhammer 40k universe is just a bunch of weaklings fighting each other; to call them an interstellar civilization is giving them too much credit.

You've already written Warhammer, are you worried about overpowering it too much? Do people who like Warhammer want you to save the world? They want to see you destroy it! What's the point of saving an empire that's a cesspool? Destroy the empire and rebuild a new one. It pleases neither side; Warhammer fans are unhappy, and StarCraft fans are unhappy too. A war is written like a turn-based game.

When writing about the Warhammer IP, authors need to be prepared. If you follow the official script, there's no point in writing it because the official script itself is prone to retconning or contradicting itself. If this were a video game, it would have died long ago. If you're going to write it in the style of a fanfic, then write it properly.

It's definitely not as easy to survive at 30k as at 40k. Templars may not necessarily lose to Space Marines, but they certainly can't catch up in terms of unit production.

Wouldn't Protoss teching up Warhammers just result in a free-for-all?

Aiur possesses a planetary-level cloaking field, unless guided by a Protoss (specifically, Zeratul, that lousy guy). Under normal circumstances, other races cannot find El.

Totoro: (Recruited by Lobster to Holy Terra) (How is the Warmaster organizing a defense line at Liongate?) (What do you mean the Golden Fleet has been besieging Terra for days?) (Where did I come here for?)

I recommend using Purifier technology to mass produce units without limit; the Protoss have very low fertility.

I don't want to look at a cesspool! 😭