Harry Potter and the Methods of Rationality

A handful of seconds later, the soldier who'd code-named herself Gingersnap returned bearing a double handful of acorns, sweating slightly in the cool but humid air from the jog that had taken her to the oak tree Neville had spotted. Gingersnap approached to where Shannon was holding a uniform-shirt with the neck tied off, in lieu of anyone having to Transfigure a bag. When Gingersnap brought her hands forward to try and dump her acorns into the holding-shirt, Chaotic Shannon, giggling, jerked the shirt to the right, then to the left again as Gingersnap made another effort to dump the acorns, until a sharp "Miss Friedman!" from Lieutenant Nott caused Shannon to sigh and hold the shirt still. Gingersnap dumped her acorns into those accumulated, and then headed out for more.

Somewhere in the background, Ellie Knight was singing her very own version of the Chaos Legion's marching song, and around half the other soldiers were trying to step along with it despite not knowing the tune in advance. Nearby, Nita Berdine, who had a high Transfiguration score, finished creating yet another pair of green sunglasses, and handed them to Adam Beringer, who folded up the sunglasses before tucking them into his uniform pocket. Other soldiers were already wearing their own green sunglasses, despite the cloudy day.

You might guess that there was some sort of incredibly complicated and fascinating explanation behind this, and you would be right.

Two days earlier Harry had been sitting amid his bookcases in the comfy rocking-chair he'd obtained for his trunk's cavern level, pondering silently in the quiet span between classes and dinnertime, thinking about power.

For sixteen Chaotics to defeat twenty-eight Sunnies and twenty-eight Dragons they would need a force amplifier. There were limits to what you could do with maneuver. There had to be a secret weapon and it had to be invincible, or at least moderately unstoppable.

Muggle artifacts were now illegal in Hogwarts's mock battles, banned by Ministry edict. And the trouble with finding some other clever and unusual spell was that an army twice your own size could brute-force Finite almost anything you tried. The Sunshine Regiment might have missed that tactic with the Transfigured chainmail, but nobody would miss it again now that Professor Quirrell had pointed it out. And Finite Incantatem was a brute-force counterspell which required at least as much magic as the spell being canceled... which, if you were severely outnumbered, made it a whole new order of military challenge. The enemy could Finite anything you tried, and still have enough magic left over for shields and volleys of Sleep Hexes.

Unless, somehow, you could invoke potencies beyond the ordinary strength of first-year Hogwarts students, something too powerful for the enemy to Finite.

So Harry had asked Neville if he'd ever heard of any small, safe sacrificial rituals -

And then, after the screaming and the shouting had subsided, after Harry had stopped trying to argue about Unbreakable Vows and just given up the whole thing as impossible from a public relations standpoint, Harry had realized that he hadn't even needed to go there. They taught you how to invoke potencies far beyond your own strength in ordinary Hogwarts classes.

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.

Defense. Charms. Transfiguration. Potions. History of Magic. Astronomy. Broomstick Flying. Herbology...

"Foe!" screamed the voice from above.

It was a good thing that Neville Longbottom hadn't the tiniest idea that his grandmother was watching; or he would've been more self- conscious about screaming scary battlecries at the top of his lungs while casting Luminos every three seconds as he rocketed through a dense forest of trees, hot on the tail of Gregory Goyle.

("But -" Augusta Longbottom said, her expression showing almost as much astonishment as worry. "But Neville is afraid of heights!")

("Not all fears last," said Amelia Bones. The old witch was favoring the great screen before them with a measuring gaze. "Or perhaps he has found courage. It is much the same, in the end.")

A glimmer of red -

Neville dodged, very nearly into a tree but he did dodge; and then Neville somehow also managed to dodge almost all of the branches before they smacked him in the face.

Now Mr. Goyle's broomstick was pulling further and further away - even though the two of them were riding exactly the same broomstick and Mr. Goyle weighed more, somehow Neville was still falling behind. So Neville slowed down, pulled back, angled up out of the forest and began to accelerate back toward where the Chaos Legion still marched.

Twenty seconds later - it hadn't been a long chase, just an exciting one - Neville was back among his fellow Chaotics, and dismounted his broom to walk on the ground for a little bit.

"Neville -" said General Potter. Harry's voice was a little distant, as he walked carefully and steadily through the forest, his wand still applied to the almost-finished Form of the object he was slowly Transfiguring. Beside him, Blaise Zabini, working a smaller version of the same Transfiguration, looked like a shambling Inferi as he stumbled forward. "I told you - Neville - you don't have to -"

"Yes, I do," said Neville. He looked down at where his fingers grasped the broomstick, and saw that not just his hands, but his whole arms were shaking. But unless anyone else in Chaos had been practicing dueling for an hour a day with Mr. Diggory, and then practicing their aim in private for another hour afterward, Neville was probably the best shot from a broomstick even after taking into account that he wasn't a very good flyer.

"Good show, Neville," Theodore said from where he was walking ahead of them all, leading the Chaos Legion forward through the forest while wearing only his undershirt.

(Augusta Longbottom and Charles Nott exchanged brief astonished glances and then wrenched their gazes away from one another as though stung.)

Neville took a few deep breaths, trying to steady his hands, trying to think; Harry might not be good for deep strategic thinking while he was in the middle of an extended Transfiguration. "Lieutenant Nott, do you have any idea why Dragon Army just did that? They lost a broom -" The Dragons had started the combat with a feint to provide a distraction for Mr. Goyle's approach through the forest; Neville hadn't realized there were two brooms attacking until almost too late. But the Chaos Legion had gotten the other pilot. That was why broomsticks usually didn't attack before armies met, it meant a whole army would concentrate fire on the broomstick. "And the Dragons didn't even get anyone, did