If I have read the volume 1 of the sixth edition rules correctly one can not have absorption of a mental attack. Short of the GM allowing such, any other way to have Mental attacks absorb and increase a power? 

I may be overlooking something here, but the rules don't specifically say, "A character cannot use Absorption on attacks by Mental Powers." All it says is, Absorption only works on attacks that do BODY. Admittedly, few Mental Powers do BODY, but unless the GM ruled otherwise a character could Absorb from, for example, a Mental Blast with the Does BODY (+1) Advantage.

 

 The "way to have Mental attacks absorb and increase a power" is to use the optional rules for Absorbing from Mental attacks on APG 80.

 

Good luck with the rat ranching!