Hmmm. I think you're on the right track.
Among other things, the vampires are driven into evil action by the cabalists. Otherwise they would be inoffensive, right?
Still, it looks to me as though the cabalists have all the firepower. Can your vampires prevail against them?
Something that could be a predator of vampires would have to be one bad critter.
Of course, vampires would have to have some form of a defense as anything that has a predator has a defense of some sort.
Perhaps vampires can make small telepathic suggestions, maybe even move small items telekinetically.
Perhaps some form of camouflage.
Of course, a vampire that has just fed would be quite powerful, considering.
Perhaps the cabalists force feed their captured vamps and then drain their essence to fuel their ancient leader?