Help

Carriers and Reavers (and the hero Carrier and Reaver) are the only ones that can do so through a queue; you need to set up the button and reqs in Firegraft as normal, and also give the Carrier or Reaver an IsWorking animation in iscript. The problem with this is that the unit will appear wherever the Carrier/Reaver was when it started training.

Alternatively, it is possible, if you have the latest EXE update list, to make Spawn Broodlings create units normally. Not much I can say without knowing how much you know and exactly you want to do.

I want to make an unit can train unit like a building

Then you'll need to use the Carrier or Reaver, as I described, but there are issues with that, as I also described, so you'll need a low build time and/or to stop the Carrier/Reaver from moving while training somehow.

Why not another unit? Why it's must be carrier and reaver?

It just does. The Carrier and Reaver, and their heroes, can build units like that; no other mobile unit can.

Does it matter if the unit trained is air/ground? also, if i tell it to train a ground unit over impasssable terrain, such as water, what happens?

Either air or ground units can be trained. A ground unit trained over impassable terrain will flail to the nearest passable terrain, and then act normally.

When I so much as hover over the button it insantly crashes, why does that happen?

Probably *.TBL error.

So, the only problem with having a non-Carrier/Reaver build another unit is the lack of a queue?