Prince Stennis is a Spy. He has 5 strength in the Close Combat row, but you play him on your opponent’s side, where he adds to their total. In return you draw 2 cards.
Since gwent hands don’t refill between rounds, those extra cards are very valuable. Just be aware that his 5 points go to the other player, so he’s best played early in a round you don’t mind losing, or when you’re already well ahead.
You get the only copy in the Northern Realms starter deck when Geralt learns gwent in White Orchard.
