Mind Reading at Rank 7 plus Subtle power feat. Mind Redaing is a 1PP/rank power and the subtle power feat cost 1 PP. Total 8. The DC is 15 +PP spent, that should makes DC: 23. Highbrow rolled 12 + 10 (Skill) + 2 (Cedric aid another) = 24. It should be fine, or did I make a mistake in that calculation? So we should have a subtle mind reading device at rank 7.