Basically you join a game at like level 1, after being rushed to act 5. The maker of the game must stay in your party and kill baal. After this, you at level 1 will be granted acess to make nm games. Rinse and repeat to get to hell level.

Its basically so you can do Chaos runs in hell, and level fast there. Don't know if I really explained it well, its just basically there to allow for low levels to level fast.

Who Delivers ten times out of ten?