Rethink, Uncommon 1/1/1
Quick.
If all cards in hand are common:
Replace your hand with common cards.
else:
Replace non-common cards in your hand with common cards.
With this Uncommon card necessarily in hand, the initial condition will never be true. As it's written now, playing it when the rest of your hand is Common will do nothing. (This is easily fixed by adding the word "other" before all, of course.)
Are the cards meant to be replaced with Commons from your deck or at random?