Magician Ward

After exiting his dormitory room, he saw Stiyl, who he had said goodbye to a while back,
hanging up things that looked like trading cards around the hallway.
“What are you doing?”
“As you can see, I am spreading a barrier and putting up a temple here.” Stiyl said as he
worked. “Since we can’t be certain that some other magician won’t make a move on
Index while we’re preoccupied with Misawa Cram School. Well, I think it’s merely
temporary peace of mind, but optimistically, leaving Innocentius here should at least
buy her time to escape.”
Innocentius.
Though Kamijou didn’t have any memory, his knowledge was telling him that that was a
humanoid-shaped ultimate weapon made of three-thousand-degree-Celsius flames that
had an automatic tracking ability. The weakness was—
“It can only be used inside the barrier of the scattered runes and will be unable to
maintain its form if the runes are destroyed, right?”
“...Let me tell you something,” Stiyl’s ears twitched. “That definitely doesn’t mean that
my power is inferior to yours. There just happened to be a geographical problem. If
there were no sprinklers then...”
“Eh? Did we fight before?”
Kamijou only had knowledge and no memories. Therefore, even though he knew how to
beat Innocentius, he didn’t know where that knowledge came from.
“Ugh... It wasn’t even worth remembering in the first place. Is that what you’re saying?”
Stiyl moved along the conversation, having misunderstood something. “Well, fine. Once
I put up one last rune, the barrier will be fully prepared, and then we can head for our
primary objective... How troublesome. I have to set up a boundary to keep off magicians,
but I can’t make it too strong or else that girl will notice it.”
Despite muttering a complaint, Stiyl looked very happy somehow.

- Toaru Majutsu no Index Volume 2, Chapter 2 Part 2