How could one describe it?
The flying monster's wings had already turned into a mechanical form, and the rest of its body might be the same.
Perhaps the spider-type monster's legs had also become machines, and some things had been added, such as... wings!
This monster could have been a tiger but now had a huge mechanical stinger on its back.
Basically, everything had been modified.
The monsters that they saw outside were probably just to prevent others from seeing them. They were indeed normal monsters!
What was the Hundred Beasts Mountain Villa doing?
Moreover, these monsters were indeed surrounded by demonic energy.
Black demonic energy.
"F*ck! What the hell is this?"
"These people modified these monsters? What the f*ck? Such a thing can be done in Fate?"
"And there's demonic energy. What's going on? Oh my god!"
...
All fear came from the unknown.