(deleted my previous response - Shaman Aura does NOT trigger on being defeated)
I had always read Shaman Aura to be a save that the Felucian rolls to stay alive. If it triggered on defeat, Felucians could use it. But the actual wording says "Felucian followers within 6 squares cannot have their Hit Points reduced below 10; save 6." In that regard, it appears to be a save triggering on the Felucian taking damage. In that case, the Felucian would not be able to use it if shot by an attacker standing in a force bubble.
And this last part goes back to a thread I posted a couple weeks ago:
http://www.bloomilk.com/Forums/default.aspx?g=posts&t=14197Also, "; save 6" is the wording to avoid an effect. I always read it as "with a save of 6," which is the wording to benefit from an effect. I don't if that's how everybody else always read it, too. Maybe I was the only one. In any case, if everybody always read it as "with a save of 6 hit points can't be reduced below 10" then I guess we keep doing that?