Catch [2]
'That should be what he's thinking, right?'
Damien was able to easily read the flow of Maveth's thoughts, because he was the one who created it.
Maveth's carefulness had been slowly broken down by Damien's schemes. The dark beast and Grand Duke Klaus just served to perfectly wrap everything up and absolve the rest of his doubts.
Damien needed to find a way to keep up his facade while reaping all of the benefits of the plans he set up.
When Klaus died, Damien was able to sneakily devour him because Maveth didn't know what devour was. If the dark beast disappeared the same way, then suspicions would arise.
As such, Damien coughed blood as if attacking Klaus and the dark beast required him to sacrifice something. As he fell, he acted desperate and used fluctuations of spatial mana to pretend he was storing its corpse, when he was actually devouring it whole.