NEWBIE here... The Deity of Night's Spirit

Anyway, there could be a boss that you must battle in these three scenarios...

1.} You must defeat it in a time period (perhaps before it turns night, when it is at its strongest)
2.} Changing the time of day would have to be incorporated into the battle. (not so much as to it is fastidious)
3.) You can either choose to defeat it at night or day, depending on when you complete the dungeon. (This could, perhaps, boost replayability.)

Perhaps, all these scenarios could be incorporated into a massive boss battle (doubt it)

The Boss' Appearance and Mechanics
The boss looks like your typical phantom (at night), except he wields these black orbs and a scythe. In day mode, the orbs disappear. Also, in the daytime, the scythe is a staff with slightly different properties. The corresponding weapon for this boss, well Link will have to use a sword, staff, or other implement to change the time of day to rid him of the pestering orbs. For these orbs purpose aren't only for attacking, but to regenerate the boss once his main body is defeated. There are seven orbs in total, destroy the orbs using the light of the day somehow. I dunno, I've gotten passionate and typed to much, sssssssorry.