i left the festival zone after the second stage for a few moments to take care of some things, and when i got back umbra's veil it says ''Defeat Nightmare Lord (1/1)'' and when i went over the the cemetery to go fight him, he wasn't there. all that work i put into the first and second round was for nothing

I'm sorry.

I'm not really sure why this would be.

If you exit the zone before Stage 3 begins, the boss technically won't spawn b/c the script just looks for those who are actually in the zone when the stage begins.

However, if you re-enter the zone during Stage 3, he should be spawned for you at that time.

Since this was something that happened this morning, there won't be anything I can test or look for at this point. =\