Level 9 gnome mindcrafter, mental shield cost 5/T.

P: 20(66) ... M: 4780
You activate your mental shield.
P: 11(66) ... M: 4781
P: 6(66) ... M: 4782
You turn off your mental shield.
P: 2(66) ... M: 4783

(Activated using the sequence of keys Ctrl-i, e -- and obviously, concentration ticked a couple times in there.)

I'm not including a paragraph about "I guess this could be intentional..." because I've decided that that sort of comment isn't useful in a bug report, since the purpose of the bug report is partly to find out whether or not it's intentional.

I'm also hoping that if I had been in combat, that the extra DV / PV from the mental shield would still be active right up until the last moment of that last turn when I turned it off.