Many of the best traps are simple. You just have to think about it, and hope your victim doesn't.

A long white ribbon shot out of the crack in the wall. The ribbon just kept coming, weaving itself into some kind of shape next to Anubis, and my first thought was, My god, he’s got a magic roll of toilet paper.

I pulled out Riptide.

I touched the combination lock. I concentrated so hard I felt like I was dead-lifting five hundred pounds. My pulse quickening. A line of sweat trickled down my nose. Finally I felt gears turning. Metal groaned, tumblers clicked, and the bolts popped back. Carefully avoiding the handle, I pried open the door with my fingertips and extracted an unbroken vial of green liquid. Hal exhaled. Thalia kissed me on the cheek, which she probably shouldn't haven't done while I was holding a tube of deadly poison. "You are so good," she said. Did that make the risk worth? Yeah, pretty much.

And when demigods use cell phones, the signals agitate every monster within a hundred miles. It's like sending up a flare: Here I am! Please rearrange my face!

Spontaneous combustion IS a form of harm, Mr. D," Chiron put in.

Rowww!” Bast wailed. The wrecking ball rolled straight over her, but she didn’t appear hurt. She leaped off and pounced aain. Her knives sliced through the metal like wet clay. Within seconds, the wrecking ball was reduced to a mound of scraps. Bast sheathed her blades. “Safe now.” “You saved us from a metal ball,” Sadie said. “You never know,” Bast said. “It could’ve been hostile.