"Try throwing the ball out of the border", Valerion said. Adrien picked up the ball and did as instructed; when it reached the line, it bounced off in mid-air and back towards them, as if hitting an invisible wall. He caught the ball as it bounced back, then placed it down on the table. "Wow", he commented, laughing. "What sort of spell is that?".

"It's a... somewhat unconventional use of defense magic", Valerion explained with a soft giggle.

"I see", Adrien replied, beaming. He walked towards the line and tried to touch it with the tip of his toe; to his surprise, he realized that the barrier did not affect his foot, or the rest of his leg. He walked in and out of the border a few times, nodding and smiling; then he picked up the ball and walked towards the line holding it. When the hand that was holding the ball reached the limit, he distinctly felt the resistance of the invisible wall - his hand could slide through, but the ball would be held back no matter how hard he pushed. He turned towards Valerion, grinning. "Brilliant -- really brilliant", Adrien said.