He tried to fool the green owl into going back to the Nightmare Realm.
He feared that Auri would kill him if he shut off the passage, so he tried everything he could to tell Auri to go inform the queen that they should prepare a bigger army to attack the wizarding world.
Once Auri crossed into the Nightmare Realm, Angor closed the passage right away while putting on a show that he "accidentally" messed everything up.
"Then the white mist disappeared, and you all can see the rest."
"Anything else you found worth noticing?" Sunders asked.
"… There is, now I think about it."
"Such as?"
"The monsters, they all recognized me. They called me 'Shava'. But I don't know that name. Maybe they mistook me for someone else? That's good though, at least I can blend in with them and learn stuff from Auri. I did it because they think I'm Shava."
Sunders shook his head. "Do you think wizard-level monsters can misjudge people like that?"