Opener of the Way adds the cosmic horror of Yog-Sothoth. He changes the fundamental laws of reality. With his ability of the Million Favored Ones, his units are able to promote for free after combat. Cultists promote to Mutants, Mutants become Abominations, and Abominations become Children of Yog-Sothoth. (Children of Yog-Sothoth can fragment into as many Mutants as are in your unit pool.) He also has the Dragon Rising and Dragon Descending spellbooks, which can only be used once per game (they are flipped upside-down after use). These give him potent one-time boosts which are real game-changers. Other spellbooks let him rain death from the sky; summon monsters from enemy-held gates; and channel raw Power into a Battle. And of course, Yog-Sothoth gives you the ability to move from Gate to Gate without passing through intervening Areas.
In our playtests, Yog-Sothoth has proven to be an extremely powerful faction, as befits the status of the One-in-All. Other players have learned to keep one eye cocked at the Opener of the Way, because he has powers that produce sudden upsets and reversals of fortune.