spawns.txt

<event>
  <outcome affected_mobs="enderman, zombie, creeper, skeleton, spider">
    <conditions_group>
        <conditions>
            <world>world</world>
            <spawn_reason>natural</spawn_reason>
        </conditions>
    </condition_group>
    <action_group>
      <actions>
        <cancel_event/>
      </actions>
    </action_group>
  </outcome>
</event>