"Do it again," she said.

"But I've got it down," I protested. "We should try something else. I was reading the other part of the book - "

"You have no business doing that yet," she scolded. "You think this is exhausting? You'd pass out attempting one of the more advanced spells. Now." She pointed at the hard desert floor. "Again."

I wanted to tell her that it was impossible for me not to read ahead in a book. It was just how I operated with all my classes. Something told me now was not the best time to bring that up.

She made me practice the throw over and over. Once she was convinced I had it down, she had me work on increasing the fire's heat. I finally managed to get up to yellow but could go no farther. Then I had to work on casting the spell without the ashes. Once I reached that milestone, it was back to practicing the throws. She picked various targets for me, and I hit them all effortlessly.

"Just like Skee-Ball," I muttered. "Easy and boring."

"Yes," Ms. Terwilliger agreed. "It's easy hitting inanimate objects. But moving targets? Living targets? Not quite so easy. So, let's move on to that, shall we?"

The fireball I'd been holding above my hand vanished as shock shattered my control. "What do you mean?" If she expected me to start aiming at birds or rodents, she was in for a rude awakening. There was no way I was going to incinerate something alive. "What am I supposed to hit?"

Ms. Terwilliger pushed her glasses up her nose and backed up several feet. "Me."

I waited for the punch line or at least some further explanation, but none came. I glanced behind me at Adrian, hoping perhaps he might shed some light on this, but he looked as astounded as I felt. I turned back to the singed ground where my earlier fireballs had struck.

"Ms. Terwilliger, you can't ask me to hit you."

Her lips twitched into a small half smile. "I assure you, I can. Go ahead, you can't hurt me."

I had to think a few moments for how to phrase my next response. "I'm a pretty good shot, ma'am. I can hit you."

This earned an outright laugh. "Hit, yes. Hurt, no. Go ahead and throw. Our time is running out."

I didn't know how much time had passed exactly, but the sun was definitely lower in the sky. I looked back at Adrian, silently asking for help in dealing with this insanity. His only response was a shrug.

"You're a witness to this," I told him. "You heard her tell me to do it."

He nodded. "You're totally blameless."

I took a deep breath and summoned my next fireball. I was so frazzled that it started off red, and I had to work to heat it up. Then I looked up at Ms. Terwilliger and braced myself for the shot. It was more difficult than I expected - and not just because I was worried about hurting her. Throwing something at the ground required almost no thought. The focus there was on aim and little else. But facing a person, seeing her eyes and the way her chest rose and fell while breathing . . . well, she was right. It was entirely different from hitting an inanimate object. I began to tremble, unsure if I could do it.

"You're wasting time," she warned. "You're sapping energy again. Throw."

The command in her voice jolted me to action. I threw.

The fireball flew from my hand, straight at her - but it never made contact. I couldn't believe my eyes. About a foot in front of her, it hit some kind of invisible barrier, smashing apart into small flames, which quickly dissipated into smoke. My jaw dropped.

"What is that?" I exclaimed.

"A very, very powerful shielding spell," she said, clearly enjoying my reaction. She lifted up a pendant that had been hanging under her shirt. It didn't look like anything special, just a piece of unpolished carnelian wrapped in silver wire. "It took incredible effort to make this . . . and requires more effort still in order to maintain it. The result is an invisible shield - as you can see - that's impervious to most physical and magical attacks."

Adrian was by my side in a flash. "Hang on. There's a spell that makes you invulnerable to everything, and you only now just thought to mention it? You've been going on this whole time about how Sydney's in danger! Why don't you just teach her this one? Then your sister can't touch her." Although it didn't seem like Adrian was about to attack her as he had Marcus, he was almost just as upset. His face was flushed, his eyes hard. He had clenched his fists at his side, but I didn't even think he noticed. It was more of that primal instinct.

Ms. Terwilliger remained strong in the face of his outrage. "If it were that simple, then believe me, I would. Unfortunately, there are a number of problems. One is that Sydney, prodigy that she is, is nowhere near strong enough to cast this. I'm hardly strong enough. The other problem is that it has an extremely short time frame, which is why I've been so adamant about a schedule. It only lasts six hours and requires so much effort that you can't just cast it and permanently keep it on you at all times. I'm already worn out and will be even more so once it fades. I won't be able to cast it - or hardly any other magic - for at least another day. That's why I need Sydney to be prepared at all times."

Neither Adrian nor I said anything right away. I'd taken note of her weary state when she got in the car but hadn't thought much more about it. As we'd continued to practice out here, I'd observed her sweating and looking more fatigued, but I'd written it off to the heat. Only now could I fully appreciate the extent of what she had done.

"Why would you go to so much effort?" I asked.

"To keep you alive," she snapped. "Now, don't make this a waste. We've only got one more hour before it wears off, and you need to be able to aim at someone without thinking twice. You hesitate too much."

She was right. Even knowing that she was invulnerable, I still had a difficult time attacking her. Violence just wasn't something I embraced. I had to push down all my inner worries and treat it exactly like Skee-Ball. Aim, throw. Aim, throw. Don't think.

Soon, I was able to fight past my anxieties and throw without hesitation. She even tried moving around a little, just to give me a better feel for what it'd be like with a real foe, but I didn't find it to be much of a challenge. She was simply too tired and unable to run around or dodge me. I actually started to feel bad for her. She looked like she was about ready to pass out, and I felt guilty sizing up my next shot and -

"Ahh!"

Fire arced from Ms. Terwilliger's fingertips just as I released my fireball. My shot went wide, the ball disintegrating before it got anywhere near her. The fire she'd released passed me, about a foot away. With a weary grin, she sank to her knees and exhaled.