So, if a target character possessed by an entity with a stop click power is attacked-- and would be using that power by selecting it via Possession-- even though the "stop" effect isn't granted through the entity, Blue Devil's trait will still activate because the power was revealed (and is being used) as the dial was turned?

Interesting, if true.

How are you getting this from what is ruled?

It has to be Blue Devil doing the damage for his power to activate. If another character attacks the character, Blue Devil's power will not activate.

I was just throwing out a hypothetical. I wouldn't know if the statement is true based on how WK has ruled it. The point is if a stop click is revealed once, then it is two unavoidable damage. If it is revealed again, either later in the dial or through the use of healing powers and attacking damage, then Blue Devil gives that character two unavoidable damage.

Only if it is revealed when BD is doing the damage.

I see that now. I have bad eyes and I wasn't using my glasses when I read the ruling.