The three spell combination that Blake had just used on the greenish demon was a spell combination that he rarely used.
In fact, it was only his second time using it ever since using it accidentally the first time when facing the brownish demon.
The reason for that was Blake felt a slight weird and unusual feeling when he used the spell combination before and when he heard the screams of agony from the brownish demon.
Despite when he thought back about it, he didn't really feel anything strange about the situation, he just had a slight nagging feeling in his mind every time Blake thought about wanting to use the spell again on a demonic beast to see whether he would get the same sweet tasting soul from those demonic beasts.