Can PC be used to make me re roll impervious?

no

Usually no.

PC can only be used by your opponent on you during your turn. If he is attacking, then, obviously, it is his turn, and he cannot PC your rolls (which Imp would be your roll if it is your fig).

However, there are a few rare circumstances in wich an Imp roll. These include EE splash damage, and during the Galactus scenarion.


I hope this makes sense...

Thank you for the heads up!