Harry Potter and the Methods of Rationality

Some Chaotics laughed with her, but a queasy sensation was starting in Neville's stomach as he realized how close the Chaos Legion had come to complete disaster. If Mr. Goyle had managed to disrupt both Transfigurations -

"Report!" snapped the Dragon General, doing his best to conceal the fatigue he felt after casting seventeen Locking Charms, with more yet to come.

Beads of sweat now dotted Gregory's forehead. "The enemy got Dylan Vaughan," Gregory said formally. "Harry Potter and Blaise Zabini were each Transfiguring something dark-grey and roundish, I don't think it was finished but it looked like it would be big and hollow, sort of cauldron-shaped. Zabini's was smaller than Potter's. I couldn't get either of them or disrupt their Transfigurations, Tracey Davis blocked me. Neville Longbottom is on a broomstick and he's still a terrible flyer but his aim is really good."

Draco listened, frowning, and then he glanced at Padma and Dean Thomas, who both shook their own heads, indicating that they also couldn't think of what might be big and grey and shaped like a cauldron.

"Anything else?" said Draco. If that was it, they'd lost a broom for nothing -

"The only other weird thing I saw," Gregory said, sounding puzzled, "was that some Chaotics were wearing... sort of like goggles?"

Draco thought about this, not noticing that he'd stopped marching or that all of Dragon Army had automatically stopped with him.

"Was there anything special about the goggles?" Draco said.

"Um..." Gregory said. "They were... greenish, maybe?"

"Okay," said Draco. Again without thinking, he began walking once more and his Dragons followed. "Here's our new strategy. We're only going to send eleven Dragons against the Chaos Legion, not fourteen. That should be enough to beat them, now that we can neutralize their special advantage." It was a gamble, but you had to take gambles sometimes, if you wanted to come in first in a three-way battle.

"You figured out Chaos's plan, General Malfoy?" said Mr. Thomas with considerable surprise.

"What are they doing?" said Padma.

"I haven't the faintest idea," said Draco, with a smirk of the most refined smugness. "We'll just do the obvious thing."

Harry, having now finished his cauldron, was carefully scooping acorns into the container while the scouts searched for a nearby source of water that could be used as a liquid base. They'd come across frequent sinkholes and miniature creeks in the forest before, so it ought not to take long. Another scout had brought a straight stick that would serve as a stirrer, so Harry didn't have to Transfigure one.

Sometimes, even though you were looking straight at something, you didn't realize what you were looking at until you happened to ask exactly the right question...

How can I invoke magical powers that ought to be beyond the reach of first-year students?

There was a cautionary tale the Potions Master had told them (with much sneers and laughter to make the stupidity seem low-status instead of daring and romantic) about a second-year witch in Beauxbatons who'd stolen some extremely restricted and expensive ingredients, and tried to brew Polyjuice so she could borrow the form of another girl for purposes better left unmentioned. Only she'd managed to contaminate the potion with cat hairs, and then instead of seeking a healer immediately, the witch had hidden herself in a bathroom, hoping the effects would just wear off; and when she'd finally been found, it had been too late to reverse the transformation completely, condemning her to a life of despair as a sort of cat-girl hybrid.

Harry hadn't realized what that meant until the instant of thinking the right question - but what that implied was that a young wizard or witch could do things with Potions-Making that they couldn't even come close to doing with Charms. Polyjuice was one of the most potent potions known... but what made Polyjuice a N.E.W.T.-level potion, apparently, wasn't the required age before you had enough magical power; it was how difficult the potion was to brew precisely and what happened to you if you screwed up.

Nobody in any army had tried brewing any potions up until then. But Professor Quirrell would let you get away with nearly anything, if it was something you could have done in a real war. Cheating is technique, the Defense Professor had once lectured them. Or rather, cheating is what the losers call technique, and will be worth extra Quirrell points when executed successfully. In principle, there was nothing unrealistic about Transfiguring a couple of cauldrons and brewing potions out of whatever came to hand, if you had enough time before the armies met.