I'm trying to come up with a configuration setting which will make it impossible for monsters to appear on the surface (except for allowing spiders to appear in Roofed Forest biomes). I've got the following rules in my S:blacklistRules section:

        mobtype:monster & light:*,sky
        -((biome:29 | biome:157) & mob:spider)

But, this doesn't seem to do anything. Monsters spawn all over the surface anyway. Any suggestions?

I should mention that the log shows the "Now parsing..." lines without reporting any errors.

I've updated things to this, and it seems to be working... at least, whenever I run into a mob, it's plausible that it came out from a cave or from under a tree...

        mobtype:monster & light:0-15,sky
        -((biome:29 | biome:157) & mob:spider)