Wasn't sure how this should work. Say you have a Power Cosmic figure with Flight and HSS with a 10 movement that's in Hindering Terrain. An opposing figure has Outwitted that Power Cosmic figure's Flight ability. The PC figure uses HSS anyway, moves 4 squares out of hindering and hits the Outwit character off of Outwit. Obviously the flight ability returns but what is the HSS character's remaining movement? Does it jump back up to 10 because the Outwit was lost? Or does it stay at half (5) because the figure began its movement in hindering terrain and was not a flyer at that point?

I think it stays the halved value seeing that is what you started with.

My main question would be 1st, how did you outwit a figure with power cosmic. 2ndly even if you were to outwit power cosmic I do not think you can outwith the flight ability on a figure.

Power Cosmic prevents you from countering powers possessed by the figure, but it doesn't protect abilities. So under normal circumstances* things like Flight, Carry etc are all you can Outwit on a PC figure.

*there are some situations where the team ability can be Outwitted or ignored: Adam Warlock, for example.

Oh, and the 5 movement was a replacement, so that's what you've got until the action ends.

Necrodog is correct.

Outwit lets you counter a power or combat ability possessed by an opposing character. Flight is a combat ability. You can counter it with outwit just like you can counter duo attack, carry, swim, etc.

And as necrodog stated above, Power Cosmic only says that the character's powers can't be countered. It says nothing about abilities.

I'd vote that it stays halved until actions resolve - but there are others far more knowledgeable than I so I defer to them.