unit selectable only by triggers

[doom_sheep]

like the spells shop in warlocks when you select a mode that doesn't have pauses between rounds. you press esc to select it, but otherwise it is nowhere to be found.

how do i create this thing

 

[wc3neverdies]

mmm i don't know warlock but i think you could do this way :

You create a unit with locust ability (so it wil be untargetable) then when a player press Esc key you remove the locust abiity from the unit, do you stuff and then you add locust ability

 

[Ardenian]

If you don't care about health bars, then you can use http://www.hiveworkshop.com/forums/world-editor-help-zone-98/locust-units-pathing-276234/.
If you need health bars to show up, you might need a custom bar system.

You might want to describe what you would like to achieve furthermore.

 

[doom_sheep]

I even gave an example. I want it to be 'hidden', except when its owner activates the trigger that selects it for him.

I seem to have achieved this by placing it beyond camera bounds. I don't know if this can have some unforeseen consequences, though. I remember a crash relating to such units.

 

[Death Adder]

From your description you don't need anything more than adding the ability "locust" to the unit. (You don't have to remove the ability at any point since you can still make the player select locust units through trigger.) And probably you don't want it to have a model either.

Otherwise if you need something more, look to Ardenian's reply. He's already answered the question afaik.