Monster idea: much like with the ratking, we need a mooseseseses monster, a bundle of moose that may or may not use the correct plural of moose.
Though a “moose” monster that is in fact plural would be hilariously confusing.
EDIT: Also, here’s an idea that’s bad mostly due to potential complexity. A circadian rhythm property that skews the relative “ease of falling asleep” and “how quickly tiredness is reduced while sleeping” properties depending on the time of day, making it easier to sleep at night and thus making it harder to become nocturnal. o3o