What this product is:
While the assassin is a legitimate, playable prestige class, game masters trying to maintain some semblance of believability in their games often have a hard time justifying an assassin player character in the party. A game master might refuse to allow the class because he doesn't want to run an "evil" campaign, or out of fear that the class will clash with other party members. Players too, might shy away from the opportunity to play an assassin class in a campaign world where it is not clear what role the assassin plays (if there is one at all).
The Principled Assassin discusses the Church of Galenen, an open game content deity of assassins. But Galenen's church is more complicated that just your typical den of murderers, and the faith serves a legitimate role (of sorts) in the greater society. This product provides details regarding how Galenen came to power, the evolution of his Church, and how his followers can function in society. This product is designed to be detailed enough to provide a new level of depth while remaining generic enough to fit into almost any campaign.
The Principled Assassin touches briefly on events first referenced in Gods of the Dead, in which we introduced four open game content deities of death and undeath. However the history presented can be easily tweaked to work in your own campaigns. The references to the Great Reckoning can be ignored or altered as needed to fit Galenen into your campaign world.
Ultimately, this product offers you a ready-made mythos and institution to drop into your game setting to add a new level of detail to the world.
What this product isn't:
There are no new classes or prestige classes, and only a handful of new spells. There are other products available that already do a fine job of offering a host of new spells and magic items for assassin characters. We felt no need to recreate the wheel by creating a bunch of new magic items and spells that simply duplicate effects already available to the player.