Going places in groups is better than going alone. If you're alone, you're an easy target. A sitting moving duck. Any maleficaria hiding in the corners of the school would love to run into a solitary freshman; easy pickings. So more people is always better, right?
Well, no. Not quite.
A group of four people? Sure. Four people watching each other's backs, even if they're all just freshmen, have enough firepower to blast a monster and run for it. All of the small mals will just see the group and turn away to look for lower-hanging fruit. Five people, about the same. And none of the bigger mals are going after a puny group of four or five. Those will just stay hidden and wait for a better opportunity, wait to ambush some group of sophomores in the alchemy lab or something.
Now, a group of thirty? That tips the scales the other way. All small and weak mals are too scared, for sure. But the big ones? The ones with an appetite?
Maybe if it was thirty juniors. Maybe even thirty sophomores. Hell, thirty freshmen eleven months into the term might be too much. But thirty freshmen before the first month of the term is even out? Thirty starry-eyed fools who heard about Scorpius Lake through the grapevine, some of them before they even got inducted (he is the son of the probable-future leader of the biggest and most powerful wizard enclave in the world, after all). Thirty children, not even fifteen years old yet, who got into this hell of a school where they are facing a one in four chance of survival because that is better odds than outside, children who have spent every day since they hit puberty outside the school having to fight monsters that want to eat their tasty mana-plump bodies, children who are told, "Hey, have you heard of Scorpius Lake? He has a combat affinity and I heard he took out five mals at once in Intro to Lab the other day!" or "Lake, isn't that the kid from New York? Oh yeah I heard of him, my cousin said she was told he took out an entire nest of lyeflies when he was nine."
Thirty children who have been removed from their homes less than a month ago to go somewhere "safer", except that somewhere safer still has everything that bumps in the night going after them. Somewhere safer where they still need to cast shielding spells on their bedroom doors and even then there's a ten percent chance something nasty will manage to slip by. Somewhere safer where they only dare shower once a week because there are creatures screaming in the pipes, creatures that will suck them dry of their mana given half a chance. Thirty children who are now going to the cafeteria, accompanied by Scorpius Lake, who is sure to keep them all safe, and a group of thirty is enough that the maleficaria will surely stay away, right?
Only the small maleficaria, though.