Dark Corners of Mystara: Cloaks of Invisibility, Daggers of Poison

There's a lovely article on the Byzantine Intelligence Service on HistoryOfTheAncientWorld.com. And since Thyatis appears to be modeled after Rome / Byzantium, while Karameikos seems to be more of the Byzantium itself -- it would be lovely to not only pattern their respective intelligence agencies against the structure identified here, but also use the Faction rules from Stars Without Number for creating rival agencies / organizations and other local groups.

And while you're at it, think up some factions after lost wisdom and power from the Hollow World.