I know some folks are cool with allowing someone to use Proxy Dice and some are not.
However in the case of Mis-Printed Dice, I think we, as a community, should agree to allow people to proxy in all cases outside of official tournaments. If you have a legendary character and it's die is misprinted, simply bring the die and set it next to your deck - then substitute a D6, and we can have a game.
Thoughts?