If I could see it then that would be enough.
"The other side's magicians, it would be a good idea to assume their magic will reach."
I do not know what kind of range a regular magician has.
But if there is one person (ME) who can, then you had better assume others can as well.
I think the possibility that Hitogami has prepared a Saint to King ranked magician is good.
"Also, it's possible that a magician from the other side will be able to fill our traps.