Promotional Cards
Proxy cards and Promo cards may not be used in tournament play.  I have never used the Nude Resistance in play, but have used the V-2 Strike and Maus cards numerous times.  V2-Strike is a usefull card that does not imbalance the game.  On the other hand, I have never lost a game using the Maus.  It is entirely too devastating, especially if you have more than one.  If used, it certainly should be considered Unique and possibly add 'flankers fire first.'  Even so, I hear many complaints whenever I use it. 
U.S. SPECIAL : Nude Resistance

Play on enemy infantry unit only when your supply is depleted.

Resistance groups stepped up their efforts as the German empire crumbled.  Most wore clothes.
Automatically defeat that unit.

Unique.

This card can only be played on infantry soldier units

German Special : V-2 Strike 

Play on enemy Headquarters

As the Allies advanced steadily towards the Rhine, V-2 rockets were used to bombard Antwerp and other vital ports.

-1 die to enemy's supply roll for two turns. Unique.

German Armour : Maus

Tank

This superheavy tank never passed the prototype stage, but is an interesting what-if, it was desgined to carry a 17cm gun.

This unit has only 1MF