laminated runes

He exhaled bitterly. Thinking back, the same thing had happened when he used
Innocentius to attack Kamijou Touma at the end of July. Immediately after losing his
trump card, he would get weaker. He’d put in a lot of effort to reflect on that, but
basically all he’d come up with were methods to prevent his trump card from being
lost—like using illusion-based evasion magic tactics or laminating his rune cards. He felt
now like he’d neglected to consider the more fundamental issues.

- Toaru Majutsu no Index Volume 9, Chapter 4 Part 1