[Mojo the Avenger]

I guess it could have been a stealthy astral mage in my dominion but I doubt it. I got the message that "one of our talented astral mages has destroyed his mind." every single turn until my gift of health healed the feeblemind. Then I stopped getting the message.

It would be a hell of a coincidence for it to be anything other than a bug.

As to the other question, I needed a mage that could cast gateway to reinforce my front lines.