Does anybody here like Corvus Corax? I thought his Story was Kind of Neat. But I think I like Leman Russ the Most though as that man is a Legend among warriors.

Leman Russ - as the only Primarch, he have beaten the Emporor in two duels he didnt deafeat him in combat, but still Plus They Werewolf-like gene-sed and the culture of he's chapter is asome ;]

I don't know. I'm thinking maybe the golden throne is purely life support, so it's inhibiting that from kicking in.
From a lore point it's possible because supposedly the emperor comes back and fights the final battle against chaos. Add in the the throne is starting to fail and it seems they are setting it up for, when the throne eventually fails, he comes back and leads the final crusade.

Magnus the red. Being a great fighter doesn't matter if you have no psychic potential.

But didn't people know that he healed like that?

I highly doubt the Emperor would indulge people about how his/her anatomy worked. Let alone how to possibly kill him.

But surely people watched him regenerate. The primarchs who fought with him would have known. I like the idea that he'd regenerate once the throne failed.

Witnessing something is a far cry from understanding it. I would guess that some of the more scholarly primarchs understood SOME of how the emperor healed himself, but I doubt any had 100% certainty how. Otherwise, they would have just made another primarch of their own.

Fairly sure all the primarchs had some level of psychic ability even Russ, his wolf howl was a manifestation of it, Magnus studied and improved upon his abilities, but yes, he had a greater baseline ability as he represented that part of the Emperor.

Yea, I see what you mean. I hope they do progress the fluff past its current point so we find out.