I'd like to suggest a new series of traits which are affected by the "time" of day. Namely, day or night.
The original idea came when I was thinking about Paladins and Darkknights specifically. I had wanted Paladin to gain a moderate regen effect during the day. DarkKnight would gain a moderate refresh effect during the night hours.
Both would be stackable with other types of regen/refresh effects.
I had also thought to expand to other sphere of effect, such as light magic and dark magics.