Johannes Cabal and the Blustery Day by Jonathan L. Howard

Johannes Cabal has faced down the undead, ghosts, monsters, and Satan himself. But before all that, he fought the terrifying Bonewind, a supernatural being that devours life itself, and he did it all without leaving his house.

"Johannes Cabal and the Blustery Day" was the story that first introduced the necromancer of some little infamy back in 2004. Long out of print, it makes its belated return on Hallowe'en, of course.