invulnerable? condition

how do i check if a unit is invulnerable? i can't seem to find it.

failing that, if there was an event I could use, to add units to a unit-group when they become invulnerable, and remove them when they become vulnerable, that'd be ok too. but can't find that either.

You don't and there is no event.

Hydra that was sooooo helpful. </sarcasm>

Are you giving them invulnerability through triggers or is it through some other means?

...It's the truth, there is no way to check if a unit is invince through triggers alone.

units can get invulnerability from a number of triggers, and from potions. if i have to mess with every way to get invulnerability, and keep track, i won't bother. i hope that's not the only option :-(