There's a big question going on at the SotM forums on BGG (http://boardgamegeek.com/thread/1211243/omnitron-beaten-single-turn). The answer, to most of us experienced players, is fairly obvious, but the OP is really struggling. A couple people here have chimed in, but I figured I'd see if anyone else had a good answer for it that would help clarify some more.
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Based on what I read the proper ruling has been laid out but the OP feels it should work differently. No matter what I think that's an awesome use of Wrest the Mind. It won't kill Omnitron but he gets the worst of it compared to Visonary.
Crush your enemies, drive them before you, and laminate their women! - Guise, Prime Wardens #31