Few creatures embrace shadow magic without both a compelling reason and a measure of desperation. Not many visit the Shadowfell willingly, let alone pledge a shard of their souls to it. Yet that is exactly what assassins, and other practitioners of shadow magic, do to gain their power.
As an assassin, you cede a portion of yourself to the Shadowfell, replacing a fundamental part of your being with a dark reflection of your true self. At times, you can manifest this twisted image in place of your body so that you can face attacks with little cause for concern. Also, the infusion of shadow magic allows you to spot the weakest points in a victim’s defenses. With a few moments of study, you can reduce even the stoutest warrior to a corpse.
If others know that you are an assassin, you might find that few trust you. In some civilized realms, the study of shadow magic and assassination is banned on pain of death. In the past, and as a response to the outcry against them, assassins formed coteries, or guilds, of like-minded slayers, and each one delves into the study of shadow magic and develops unique methods of killing. A guild provides you with a measure of protection, and its grandmasters expect obedience and fealty. The wars between guilds, and the struggles within them, might never spill into mass battles, but they still leave dozens of slain folk in their wake.
As an assassin, you are an outcast. You traded away part of your soul for the power of death. Perhaps you seek justice against a powerful enemy, or maybe you had no other way to preserve yourself in the face of a bleak, uncaring world. Whatever drew you onto the assassin’s path, you are an avatar of death and a trained killer from whom few can escape unharmed.