One of the attacks in my game is doing seemingly infinite damage and I'm not sure why.

The link: https://scratch.mit.edu/projects/965643602/

More detail please. Which attack, for example?

The boomerang attack specifically is one-shotting every enemy type I have added, even when I change their hp to be absurdly high, it still one-shots

You have a lot of sprites and scripts so it's a lot of work for anyone helping to look for conflicts. If you at least identify the relevant sprite and script we can potentially check that.

My recommendation with large projects is to make a stripped down copy to make it much easier to isolate the issue.

Your game is very messy, so it's harder to find the issue, my idea is that : when you throw the boomerang, it infinitely damages the enemy instead of attacking it once, certainly since it directly puts the hp to 0, it probably attacks the enemies a bunch bunch of times

The sprite that is inflicting the damage is the “Boomerang damage” sprite, and the sprite that tells it to do that is the “Boomerang projectile” sprite.

Why is the boomerang damage being cloned?

it's to make multiple damage effects pop up since the boomerang is multi-hit