How made an unsellectable unites?

[Gev]

The thing that im searching is not desellect unite when im sellectiong it. I need to make its unsellectable at all. I know that its possible Becose i got a Tornado unite that cant be sellected. I dont know how but its cant be sellected and have no Health bar. Is it Model or there is some options that i must set?

 

[Risen]

Add locust ability to unit.

 

[Gev]

Oh i sow that twister got that ability but didnt knew that there is the key. Thx a lot of ++++