The Mordor Spider Keeper is a type of mercenary captain from whom you can hire the spine-chilling Mordor Spiders. They spawn in Spider Pits, which appear in Nan Ungol, the southwestern most part of Mordor. They often spawn riding atop a Mordor Spider. You can hire Mordor Spiders and Mordor Spider riders and unmounted Orcs from the spider keeper for a fee of silver coins, but only if your Mordor alignment is at least +250. Note that these units are a good unit choice as they have orcs riding the spiders and the spiders fight quite nicely themselves.