Sargtänzer

You get it from completing his companion quest

"Coffin Dancer" is a novel written by Jeffery Deaver. It is a popular series of crime novels featuring the forensic detective Lincoln Rhyme. Lincoln Rhyme, a quadriplegic forensic expert, and his partner, Amelia Sachs, are on the hunt for a ruthless assassin known as the Coffin Dancer. The Coffin Dancer is a professional killer who leaves distinctive clues at his crime scenes, taunting the authorities. No - it's not the Coffin Dance meme.