{
        "mod":"mana-and-artifice",
        "gamestage":"disable_mana_and_artifice_mobs",
        "result":"deny",
        "onjoin":true
    }

This is supposed to disable MaA mobs from spawning if you have that gamestage. It only works in a 100 block radius around the player though, and mobs can spawn outside of that radius. A player with the gamestage would notice no difference then. A config to increase the radius would help fix this.