"Do you have any idea how dangerous what you're playing with is, Stiles?" Deaton demanded, and Stiles breathed, mostly tuning him out.

"I do, actually," Stiles said, and flipped the knife into his hand without looking; he paused for a moment, but he'd already mentally marked out where to cut that would leave him free to use his hands and not be likely to keep bleeding, "though few of you seem to believe it, I almost always know pretty well how dangerous what I'm doing is."

Deaton kept talking, growing a little louder now, but Stiles ignored him, slashing into the meat of his forearm and allowing the blood to fall; the candles around him all became tall pillars of unwavering flame, and Stiles opened his eyes and threw out his power and his will, seeing the magic shimmer in the air as he dug deep, calling for gods so old their names had been forgotten.