Vampires Vs. Werewolves
From AmtWiki
The eternal struggle between the Lupine moon-worshippers and the undying bloodsuckers provides a great variety of opportunity for adventure. Place one or more Werewolves (or Cats, or Rats or whatever) on one side, and a Vampire and/or Nosferatu or two on the other. Have them lead the normal players in battle against the other team. Be sure the Lycanthrope you choose can injure the Undead, and vice versa, even if this means just making a “quest only” rule that the Monsters may harm one another normally. Other ideas include having the Lycanthropes defend their den against whatever the minions of darkness can throw against them, or turn it around and have the Lupines lay siege to the graveyard lair of the Vampire Lords.