Because, given the circumstances, is there much chance Gloryhammer won't go for an Escaped from Hell moment?
- Confirmed. Only, not with Gloryhammer.
That's why Zargothrax arrived earlier in time than Angus and the Hootsman arrived the earliest of all as he was the first through the portal.
Angus XIII going to hell may only ensure his corruption instead of preventing it. But to complete the symmetry, he will be opposed by a Zargothrax clone that has been raised to be good (probably by Ralathor).
- Jossed. Junior is just as evil, hateful, and as sworn to darkness as his progenitor was.
While they ultimately saved the day by creating the Hammer of Glory, they also created the Knife of Evil, a weapon that seemingly has no other purpose than to turn its victims evil. At the very least, they didn't have everyone's best interests at heart.
The Zargothrax that Angus XIII fought in Legends From Beyond the Galactic Terrorvortex was from the future, like himself. Before Angus arrived, he defeated his earlier self, who decided to ally with Angus out of revenge.
- Jossed. The official timeline shows mutually exclusive origins for Ralathor and Zargothrax. Ralathor comes from the Terrorvortex universe; Zargothrax is native to the prime universe.
So, despite the official timeline showing him having been born in the Terrorvortex universe, he somehow found his way into the prime universe before the events of Tales From the Kingdom of Fife. He then went through Space 1992, Legends From Beyond The Galactic Terrorvortex, "Fly Away" and Return to the Kingdom of Fife in that order.
The Starlords clearly don't care about killing innocents and, for some God forsaken reason, created a knife that seems to have the explicit purpose of turning people evil. They don't seem to be very nice and Angus will quickly betray them and fight against them.
On the surface, his all-destroying motives wouldn't make much sense since this would destroy him as well. No doubt there was a price to be paid for his sorcerous powers, and it could be that the forces of chaos took his sanity.
When Zargothrax made his pact with chaos (as shown in the music video for "Keeper of the Celestial Flame of Abernathy") we see him draw his own blood with a knife. It's not explicitly made clear, but this could very well be the Knife of Evil, and perhaps a simple cut is enough to be corrupted by it. Perhaps the term of his pact was to make himself completely evil using this artifact. That's how he went from being "a simple peasant" to the Omnicidal Maniac we know him as.