Engorgio

Engorgio is the Engorgement Charm — fourth-year Charms, paired with its counter Reducio. Cast at a target, it causes the object to grow larger. A pumpkin becomes the size of a beach ball; a quill becomes a yardstick; a chair, occasionally, becomes a worrying problem for the room it's in. Volume scales with caster intent and skill, and the limit is generally what the caster can hold mentally rather than any hard cap built into the charm.

Hagrid is the spell's most famous regular user. The enormous pumpkins he grows in his garden patch — large enough that one is said to feed Hogwarts for a week — are the result of an annual Engorgio applied to ordinary pumpkin seeds and reinforced over the growing season. Most household applications are smaller and more practical: a too-small loaf of bread, a too-narrow door for a moving day, a quill that needs a longer reach.

The charm's most memorable on-page appearance comes from Mad-Eye Moody — actually Barty Crouch Jr. in disguise — demonstrating it on a spider in the fourth-year Defence Against the Dark Arts classroom. Crouch grows the spider into a hand-sized monster before reverting it with Reducio. The lesson, ostensibly about the Cruciatus Curse, lingers slightly more on the Engorgement Charm's casual cruelty: the spider is just a prop, and the demonstration moves on to worse things.

Effects on living creatures are inconsistent. The charm generally works as expected — the spider grew, no harm done — but ethical wizards tend to avoid casting it on people and animals as a matter of principle. Joke products like the Weasley twins' inventions sometimes use Engorgement as a base mechanism, with predictably chaotic results.