This may be obscure or super popular im not sure, but i recall there being a (probably children's) series about a group of teenagers who go around the world to fight monsters or something. I just remember a few things, like how the power system involved the power of imagination or something (which i'm a little unsure about), but i vividly remember how there's a school bully (who i think was called stefan) who becomes a main character after the protagonist saved his life from a wizard (or something) who used pipes to nearly kill him after he tried to bully the protagonist (the chosen one) and then another time later that day in which the scene vividly describes a pin being dropped. Also, they go to a secret cave inside Uluru in one of the later books and some other stuff. Really bugging me since i loved this series a decade ago