Would it be possible to control the minimum block light by the current phase of the moon?
So if there is a full moon you have a block light of 5 or 7 and if there is new moon the block light is 0.

Already Added.

I build it from the current source and the blocklight itself does not change. Currently its just visual for players. My idea is to change the hostile mob spawn to a lightlevel of... for example 5. So when there is full moon there should not be any mob spawns.

currently I got the settings for full moon at 1.0
This is a screenshot of the full moon phase. Mobs still spawn. (or means 1.0 a blocklight of 7?)

Some more testing with incontrol mod debug:
Moonlight does not matter. Mobs spawn with an option of maxlight 4. Mobs don't spawn with a maxlight of 3.

Oh that's what you mean, will look into it.

I'd second this. When you get away from the light pollution of the cities, on a clear night with a full moon it can be almost bright enough to read a book.

I wonder if you could simulate a brighter full moon by combining HCD with something like In Control.

Thats my goal. Example:
Zombies spawn only on new moon, because its darkest (light level == 0)
Skeletons can spawn with half moon and light level below. (light level <= 2)

Mobs can still spawn under the trees if all you do is change the light.