Baal run help

[killer7]

I've done 2 Baal runs with level ~20 characters, the first time I made the mistake of going through and staying until Baal was killed. The second, I quit (save and exit, while still in the minion area) after the last minions were killed. Both times I went to nightmare mode.

When I used to play years ago I did this without going to the next level, but it has escaped me. How do I stop from going onto the next mode?

[DaRkStAr]

make sure in the quest window it says for baal "You will not complete this quest in this game" or something similar to that