The rewards shows the picture that with what splinter you have completed your daily quest. I at least have believe in this thing that we got at least one to two cards related to what splinter I have used to play ranked battles. This represents that I played with Fire splinter and got these three cards along with one rare card.
I got these 3 cards in result of wining daily quest. It was not hard to play even I enjoyed a lot but I never get satisfied with the reward for quest. It may called as luck. So my luck is in sleeping and darkness. huh?