Worker disappears while constructing

[HeroEditor]

I was wandering how does a wisp constructing works, because I want the same thing with casual worker, but I can not make it disappear.

 

[Jampion]

It depends on the race.
Your builder needs race night elf and if you want it to die after constructing, the building must have the "ancient" classification.

 

[HeroEditor]

Okay, thanks! Nevertheless it's weird.