Wilderlands Lunarbound is a mod that adds a very simple behavior that can be added to an entity's server side behaviors in their JSON asset which basically defines whether the entity is allowed to exist during the game's current phase of the lunar cycle. If not, the entity despawns.

To use, add this to the entity's behaviors on the server side of the JSON file:

"server": {
   "behaviors": [
       {
        "code": "lunarspawn",
        "lunarSpawnPhases": [ 1, 2, 3, 4, 5, 6, 7, 8 ]
       },

There are 8 phases to the lunar cycle. 1 being the new moon (moon is not illuminated at all), and 4 being the full moon. At 30 day months, each phase lasts a bit over 3 days (I think). I did not code the phases of the lunar cycle, they already exist in the game. This mod simply provides a way to tap into them to use lunar phases as behavior that moderates spawn ability. If you want further details about how the lunar cycle actually works, you'll have to dig into the code and puzzle it out. I'm still learning myself.

Mod is in early phase. I've tested it without issues to the best of my ability, and could use some other eyes on it and some feedback. If I don't hear word of any issues, I'll move it out of dev phase in it's current state.

Other features are being considered, but I'm not ready to share details at this time.