Hell, after some incidents involving Clan Belial.
Bael, Diablo's right hand, held a meeting and 'gently' asked Belial to explain what had happened. Of course, Belial had the option of not saying anything, but only God knew if he would become Diablo's snack or not if he refused to say anything.
Belial was no fool, he knew that when Bael asked for something, it meant that Diablo himself ordered the man to find out what was going on.
And Diablo's orders were absolute unless, of course, you had desires to become a snack for the Primordial Demon.
And Belial remembered very well the rule that Diablo had imposed on his servants.
The first and only rule of Diablo's army.
"Diablo's orders are absolute. Disobeying an order from Diablo is tantamount to the death penalty."
Unlike Lilith's army, which had more solid rules, Diablo's army only had this rule, and so, because of that, this being's army was chaotic but at the same time organized.
After all, everyone was afraid of Diablo, and that fear restricted their actions, thus making the army organized.
If Diablo ruled through the Demons' fear of him.
This Demon's words blatantly implied it.
"The other Demons of the 72 pillars who are allied with us, and the Fallen Angels, have already been informed of their respective jobs."
"Starting today, we will engage in an all-out war with Lilith."
"And this war must end before the meeting of supernatural beings."
Bael rose from his chair and walked towards the exit, and during all these movements, he had a distorted smile on his face.