B.P.R.D.: The Devil You Know Volume 3--Ragna Rok — Mike Mignola

The finale to B.P.R.D., Hellboy, Abe Sapien, Liz Sherman, and the rest of the bureau face off against one of their oldest enemies in the last battle to save the world.

One enemy leads to another as the B.P.R.D. finds themselves up against something--and someone--even more sinister than they believed, and Christopher Mitten draws the origin story of one of the B.P.R.D.'s most mysterious foes. 

Collects B.P.R.D.: The Devil You Know #11-15.