Not an earth shattering deal, but this DLC was $4.99 and is now listed as $0.99.
This was a special DLC, there are no trophies associated with it, but if you wanted to finish the game with your kids in its entirety like me, worth it for a buck.
Artifact Checking DLC $0.99 @ PSN [playstation.com]
Adventure Time: Artifact Checking expands the story of the original game with a brand new episode starring Marceline the Vampire Queen!
• Play through an all new side story that parallels the events of "Everything Must Go!"
• Use Marceline's unique Vampire abilities to tackle dozens of new puzzles.
• Visit new characters and locations, like the deliciously spectacular Wildberry Kingdom.