Guild Wars 2

Probably a dumb one but this isn’t I’ve been able to figure out.

I know the fractal is a mini-dungeon and a standard run usually involves running three mini-dungeons with a fourth on even numbered.

Does completing 1 mini-dungeon increase your level while the ones after are for the rewards and don’t raise your level? Or do you have to do all of them to raise your level?

Need to complete all of them to advance a level. Otherwise, a person would just run the easiest fractal over and over and reach max level without any trouble.