Well, I don't know about aliens, but who do you think founded Shantiri? Maybe someone came from Enroth, started an Empire, and then left.

Regarding the eclipses. The fifth one was predicted perfectly. If it weren't for Alaron's sluggishness and Cyrus's arrogance, it might have been possible to avoid the loss of leaders.
As for the rest, yes, Kha is unleashing all his power on humans, and he's doing it more and more often. Cyrus is in power, and he treats them like... well, you know what. The dwarves have Tolgar (?), who is also a somewhat negative character; I already mentioned the elves; and the orcs fled even earlier because of the humans. There's no one to help, and no one wants to.

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if we go back to the origins, then the demons are not to blame at all, but the Angeloffs and the Faceless, who started the war. Who are the Faceless anyway? I suddenly realized that I know absolutely nothing about them...