When "start" was shouted, the opponent's frontmost player immediately released layers of thick black fog.
Benovia recognized this fog: "Dark Element magic [Bizarre Illusion Barrier], it's able to reduce mages and magic puppets' senses and sight. The counter is the corresponding magic [Holy Dispel]."
Dark Element magic opposes Holy Element, but this school of magic isn't illegal—it's also recognized by the Mage Guild. Just, few people study it, since Dark Element magic feels uncomfortable and naturally makes people think its user isn't a good person.
Though the Mage Guild has emphasized more than once that bad people are the problem, not magic itself, and even cited examples of certain High Priests from the Holy Court, people still don't really like it, making it an extremely niche school.
Other than Benovia, no one recognized this magic.
Luckily, she recognized it and provided the method to counter it.
