As a spell-writer, you're the magical equivalent of computer programmer. You've made and copied countless spells, but this is the first time you're desperate enough to try 'hacking' one.
This is extremely dangerous, but in the heat of a duel, you've got to try something.

You must target a specific spell of your opponents (no spells can be targetless), and you must have a reasonable chance of stopping it. To do this, you need to examine the original spell's text thoroughly.

When writing down a spell, you must choose exactly how many components it needs, what kind of components they are, and what the exact wording
As you cast a complicated, powerful spell, you reach out with your magic and try to manipulate it...

This was a spell that had taken you hours to write and perfect. You focused all of your will on the intricate web of arcane energies before you, carefully reaching out as the magic coiled around your fingers. As you began to manipulate the spells' intricacies, it surged to life with a mind of its own. The energies twisted and knotted