ID	Description
-1	Used only for map-less (floating) npcs
45	Displays a warp tile (depending on the client settings). Does not display warp particles
139	Used by Hercules for hidden warps
722	Displays a debug warp tile (used by battleconfig.warp_point_debug). Does not display warp particles
127	Displays a transparent non target-able npc. Used by tmwa for area effects (magic)
400	Displays a transparent target-able npc
32767	NPCs with this ID exist only server-side and are not sent to the client. Usually you should prefer this over 127

TODO: add a transparent target-able npc with pickup cursor
TODO: add a transparent target-able npc with fight cursor