"You only considered defense."
Douglas walked back to the lectern and drew another sheet from the stack of parchment.
"A Faraday cage is a passive defense. But in a real fight, you can't just block.
You need to judge your opponent's casting rhythm while blocking, find the gap between his attacks, and then counterattack."
He suspended the sheet in the air.
It showed a timing diagram-the attacker's casting rhythm was represented by a red zigzag line, while the defender's counterattack windows were marked with blue squares.
"That's why this is a joint teaching session."
He looked at Flitwick.
Flitwick picked up where he left off.
"The Shield Charm's frequency adaptation, combined with the Mental Faraday Cage's neural shielding and an analysis of the attack rhythm-only together do these three form a complete O.W.L.s-level defensive system."
He hopped down from his raised platform and walked to the center of the classroom.
"Now, pair up. One person casts Petrificus Totalus, while the other blocks it with a Frequency-Adaptive Shield Charm, maintaining the focused state required for the Mental Faraday Cage at the same time."
"Take turns practicing."
"Five minutes."
The students began moving desks and chairs.
Spell light crisscrossed the classroom.
The sounds of shields shattering, the hum of them reforming, and the occasional flurry as someone lifted the curse from a petrified partner-the classroom became a small training ground.
Neville paired up with Harry. Harry raised his wand.
"Petrificus Totalus!"
Red light shot from his wand tip.
Neville did not step back.
His Shield Charm formed before him, its surface covered in irregular ripples-a sign of frequency adaptation, as the shield automatically adjusted its vibration pattern to match the frequency of the incoming spell.
The red light struck the shield with a dull hum.
The shield shook but did not break.