The Sabbat. They're basically the bad guys in a world already full of vampires that are looking to drink humanity dry. So, you know they're out for more than just blood. And if you're looking to play as one or make them a bigger part of your Vampire: The Masquerade game, you'll want to pick up the upcoming Sabbat book from Renegade Game Studios when it comes out.
From the website:
Brothers and Sisters in Caine, united under the banner of the Dark Father
An antagonists’ guide to the cultic fanatics of the Sabbat, this book contains everything you need to incorporate the infamous Black Hand faction into your Vampire chronicles. Inside you’ll find descriptions of the Paths of Enlightenment, the foundations of Sabbat identity, information on the Gehenna War, and details on how the Sabbat opposes the dread Antediluvians. You’ll get new tools to expand your chronicles, including Discipline powers, minions and servitors, and the horrifying Ritae of the Sword of Caine.
Sabbat: The Black Hand is a supplement for the Vampire: The Masquerade Roleplaying Game, outlining in detail the lore and background of the Sabbat, including new Paths and Disciplines, its current customs and practices, and new Storyteller resources for a richer Vampire roleplaying experience.