According to dragon mythology, Verjigorm is basically the creator of all the Horrors. One of those Horrors was different, and broke away to find some place untouched by their evil. This was Nightsky, and from its first tears were born the Namegiver races. Of those, Dayheart, the first dragon, rose up and proclaimed her Name, while the others were all given Names by Nightsky. Thus, Dragons consider themselves Nametakers, apart from other Namegiver races.
Verjigorm showed up later, and Nightsky led his children in fighting against him. In the end, Verjigorm was driven off, but Nightsky was mortally wounded in the battle. Verjigorm promised to return, and to hunt the dragons and corrupt them. That is why Verjigorm is known as the Hunter of Great Dragons. In Earthdawn's time, there were several dragons who had been captured by Verjigorm, and were being corrupted in astral space by his power. While the Dragons certainly tried to destroy as many of the creatures as possible, and others probably died during the down-cycle hunting, it is not inconceivable that some survived. Which would explain the Smoking Mirror...
