Dummy Units.
Dummy units are special units (lol, not really) meant to help you enchance the spell with better effects. For now, you must know how to create your own dummy unit in the object editor. After that, you will learn how to use them as well.
So go to the unit editor and copy-paste the footman unit. Rename it as dummy, so that you will be able to recognize it later. And now, change the following fields accordingly:
Abilities – Normal – It should include only the Locust unit ability. This will make the dummy unselectable, invulnerable and will remove its collision, allowing any unit to pass through it. By this you assure the unit cannot be detected in any way.
Art – Model File – Switch to custom and type none.mdl. This will make the unit invisible (not as invisibility, but unseen).
Art – Shadow Image – Switch the value in preset to none.
Art – Special – Delete everything there.
Combat – Attacks enabled – Switch to none.
Combat – Death Type – Switch to Can’t Raise, Does not Decay
Movement – Speed Base – Set its value to 0.
Movement – Type – Switch to Fly.
Sound – Unit Sound Set – Change its value to NONE.
Stats – Can Flee – False.
Stats – Food Cost – Set it to 0.
Stats – Hide Minimap Display – True
Stats – Sight Radius (Day) – 0
Stats – Sight Radius (Night) – 0
Techtree – Upgrades Used – Delete all.
After you have given the unit all these values you can place one on the map and notice that ingame you won’t see it. In World Editor it will appear as a box with green/black squares. That’s because the model you assigned to the unit doesn’t exist. It will disappear ingame.