Simple Question

I have a simple question to ask... how do you make a unit go ethereal?

Well, there's actually an ability called Ethereal. If you give the unit that ability, they are permanently ethereal. It's a unit ability.

Is that what you are looking for?

give the unit the "asthral" ability, that will make it immune to physical damage but it takes more magic damage.
if you just want the unit transparent use the trigger "Animation- change units vertex coloring"

anyway there is no "ethereal" only asthral :8

its spelled Asteral, get your spelling straight.

And it IS Ethereal. Its a unit ability, theres no ability called Asteral or Asthral you silly man.

I guess its name depends on the language you are playing, probably. In spanish version is "Desaparición" (Disappearing) for Bloodmage and "Forma etérea" (Ethereal Form) for orc Spiritwalk.

Salutions®

In german it's called "asthral", that's the same as "ethereal"

Well what my problem is is that I did give a hero the unit ability Ethereal and when I use it he's still the same... nothing changes at all.

I'm almost positive that it's not an activated ability. What that means is that clicking on it wouldn't do anything, any unit with the ability will automatically be ethereal. Are you trying to make a unit that can switch back and forth between ethereal and corporeal (normal) form? Or is the hero with the Ethereal ability not Ethereal?

the ability "Ethereal" will make any unit that has it Ethereal, it will move slower and be unable to attack, but cannot be attacked, will be able to cast spells and will take double damage from spells and magical damage. The ability "Ethereal Form" is totally different.

my guess would be to just make a buff