Robin Hood

Question : Was this card updated ?

Answer : Yes. The first printing of Robin Hood said
"Characters your opponents play cost more."
Future printings will say
"Characters your opponents play can't cost less than . (If they would cost less, they cost instead.)" This change impacts all versions of this effect, including the ones found on Unique cards. Any card that uses the previous wording should be read as if it used the new one.

Question : What happens if a player plays a Character for free, such as with Auraq & Kibble's effect, while their opponent controls Robin Hood?

Answer : A free card remains free even against Robin Hood!
Playing a card for free means bypassing its cost entirely, which is different from reducing it to zero.

Question : If I control Robin Hood, can my opponent reduce the cost of a card using an effect such as Martengale?

Answer : They can, but if this would bring the card cost under 2, the cost would remain 2.