Blizzard has added in a new card back to the game, the Gift of Elune card back, and it belongs to a new Puzzle! This is the second card back to be added this way, the first being the Mysteries of the Phoenix card back only a few months ago.
This card back is related to a new set of Stormwind gameplay achievements named "???" with the description "Burn my sight.".
- The first achievement has 1 criteria.
- The second achievement has 2 critera.
Completing these tasks will reward you with 300 and 500 experience respectively and the new card back. The card back internally is called "Card_Back_Jennifer_Brozek", which may name a concept artist who has previously taken part of a Hearthstone concept art challenge, though not for a card back. Don't go hounding them for answers though, that'd rude!