In Ultimate Power, p. 172, there's a +1 extra for the Mental Blast power called Mental Feedback.
As far as I can tell, Mental Feedback essentially changes the Mental Blast into a mental aura (as described in UP, p. 99) which "only activates as a reaction". My problem is that I can't for the life of me understand how it only adds +1 to the base power. This would change the cost from 4pp/level to 5pp/level, by the way.
The base power is, again, Mental Blast. To qualify for the Aura extra, the Range must be reduced from Perception to Touch (a -2 modifier), and Duration increased from Instant to Sustained (a +2 modifier). Aura (a +1 modifier by itself) also changes the Action to activate the power from Standard to Free at no additional cost. With that in mind, change the Action from Free to Reaction (a final +1 modifier). Adding all of these modifiers up: (-2) + 2 + 1 + 1 = +2. So it should be a +2 extra, shouldn't it?
Even when constructing the power from the ground up, the outcome is the same:
Base Effect: Damage [1pp/level]
Extras: Alternate Save: Will [+1], Duration: Sustained [+2], Aura (automatically changes Action to Free) [+1], Action: Reaction [+1]
Final Cost: 6pp/level
At first I thought that there might be a flaw in there somewhere. After all, the description states that the aura only activates as a reaction. If that meant that the user couldn't employ the aura offensively, it might qualify for the Limited flaw, right? Apparently not; when reading the description for mental auras, it stated that they aren't usable offensively anyway.
Am I missing something in my calculations, or is the book wrong?