Released at GenCon 2012, The Battle of Lake-town is second print-on-demand encounter deck (so, not a full expansion like the monthly decks).
Description from Fantasy Flight:
"Believed to be nothing but a legend by the younger generation of men who live in Lake-town, Smaug the Dragon descends from the Lonely Mountain unlooked for in the dead of night. The Dragon believes the people of Lake-town are responsible for the recent theft of his treasure, but the people of Lake-town know nothing of this. All they know is that if they don't stop him, Smaug will destroy their homes. Now the heroes must face the Dragon's wrath to save Lake-town from burning..."