The start of a new season of competitive play in Hearthstone always brings with it a new card back to unlock, and November's is themed around everyone's favourite in-game fisherman, Nat Pagle.
The card back is called Gone Fishin' and the artwork has just been released by Blizzard in a news post on the official Hearthstone site. Here's how it looks:
In order to unlock Gone Fishin', all you have to do is play the game and hit Rank 20 during the month of November. Keep in mind that even if the bonus stars awarded to you at the end of October push you into this qualifying zone, you'll still need to actually log in at least once this month to unlock the item.
Card backs show up in the rewards chest which is awarded at the end of each month in question. When you open up your chest at the start of December you'll find Gone Fishin' in there, along with the usual collection of bonus cards, coins and crafting dust.
Note that you can earn your chest by playing on either the Wild or Standard ladders. If you play on both though, you'll only receive one reward chest. The contents will be determined by your best ranking across both formats.