So sorry, I missed adding the group node >.<
However, the NPC killing node is specific to the plugin you use.
If you use Restrict it is: restrict.npchurt (And it can be configured for guests)
When I get a chance I will add a template of the XML to the first post too.
Thank you, managed to get the NPC hurting to work ...
Any idea about building? Players can now hurt NPCs but not build when registered and logged in.