Are Koed heroes legitimate targets to perform attribute tests on? Let's say you have an effect as well that has every hero roll but some are Koed? What happens then?

Koed heroes can only be trageted by events/powers that give life immediately...

So from my understanding Koed heroes can never perform attribute tests...

Makes sense. Since you switch the miniature for a token. Otherwise I'd assume that they aut.fail any tests.

Heroes that are knocked out are actually removed from the map and replaced by a token. as such, they cannot be affected by any effect, except one that directly grants healing. (or an effect that specifically targets a hero token/knocked out hero)

Alarmed and Felin nailed it. No.

Ok, thanks all.