After her performance

The most obvious location of where she would be is at her performance. Thanks to your new magic, and your research, you should be able to incapacitate the heroine if you act quickly enough.
Right as you were done going through your plan one last time, you heard a storm of applause from around the corner. You rolled your eyes as she thanked them repeatedly, and prepared your first spell.

Zatanna walked from around the corner, visibly tired from her performance. Perfect. As soon as she came close enough, you quickly jumped out and sent out a simple spell.

"What the-" She said, startled. "Erif fo nair-" Right as she was about to cast a spell, yours hit her in the stomach. She waited a second for her attack to appear, but nothing happened. As she gasped, she was shocked to realize that she couldn't speak. It was surprising and a b

With her main form of attack gone, you quickly sent out another, stronger spell, that knocked her out. You quickly got close to her, and searched and confiscated all of her various other tricks. Now that you have all of her tools, you thought about where to put the body.

While you were tying her hands together, you got an idea. Then you thought about it. You could just perform your "idea" right then and there, and then you could deal with her. After all, she really couldn't do much, and you could always just use your dark arts. Or you could bring her to your apartment. You do have some... extra tools that you can use for your "idea".