there are stories ... that he stands twenty feet tall , that his teeth are mobile like a spider 's , which he uses to fashion his ungodly nest , that he swoops down from the blackest sky borne on wings ten feet across to snatch his prey , carrying them past the highest clouds to rip them apart , and the leavings fall back to earth in a rain of blood and spit , what is called the pwdre ser , the rot of stars . ''