How are the Mord Wraiths described in the novel, The Wishsong of Shannara?

Mord Wraiths, also known as dark walkers, are faceless, and skeletal. They wear black robes with hoods and carry gray staffs. They have great power, creating a sense of despair around them and destroying enemies in a burst of flame. They are the creation of the dark magic contained in the Ildatch.