"Boxing Days" is the eighty-sixth issue of Fables.
Publisher's summary
Meet Dunster Happ, the most important Fable you never knew. If our friends in exile at The Farm knew even a fragment of what humble Dunster knew, they'd be in a lot less trouble right now. Mr. Happ's just one of a cast of thousands in this issue where we explore Mister Dark's past and how he ended up in that magical box in that faraway fortress so that two hard-luck mercenaries could come along one day and set him free. Featuring the guest art team of Jim Fern (CROSSING MIDNIGHT) and Craig T. Hamilton.
Plot
Mr. Dark now has an army of zombie he controls after killing them. In flashbacks, a man named Dunster Happ join a strange brotherhood named the Boxing League. His superior Burrant is killed while trying to capture Baba Yaga, making him the leader of the brotherhood. Happ recruits many sorcerers, and Mr. Dark accidentally traps himself in the box. Mr. Dark says that there is nowhere anyone can hide from him.
Continuity
Dunster Happ states that he spent seven years in the Hesse, where he and his fellow Boxers boxed the last of the "baleful Hernes." The fate of Herne and his son is explored in Fables #155 — "The Black Forest Chapter Five: Unboxing Day."