Machin Shin is the entity that roams the ways, corrupting all those that it comes into contact with and ultimately driving those people insane. I've read the theories about how Machin Shin was created yet there remains one theory that nobody has seem to mention. Aridhol. Aridhol had a waygate and when Aridhol became corrupted and fell another entity was created. Mashadar. Now during the trolloc wars the ways became corrupted with the entity known as Machin Shin but it was never explained if that perhaps a part of Mashadar had seeped into the ways through the waygate in Aridhol. It could have been possible that trollocs or an army of the darkone were seeking refuge of the ways from Mashadar and in the process a part of Mashadar was trapped inside the ways, unable to escape the piece evolved and became something else.