The Blood Lust is a special ability that is inherent in all vampires, however, not all vampires can access this form instantaneously. When in Blood Lust, a vampire begins to lose its beautiful features, and resemble rabid animals or even gargoyle-like abominations. They exhibit fangs that are further elongated coupled with dagger-sharp teeth, eyes that flash a brighter shade of red, pointed ears, nostrils that resemble a common vampire bat, arms to grow out chiropteran wings, bipedal legs, claws, and are constantly surrounded by a hazy red ink-like mist.
Blood Lust is usually accessed by a vampire when it is deprived of blood for a long period of time, consequently making them feral and driven by pure instinct alone. When they begin to consume blood, the Blood Lust reaches its final stages of preparation and thus comes to light for the vampire to assume control over.
The Blood Lust is to vampires what the Munin Howl is to werewolves, but unlike werewolves, the Blood Lust poses a risk to the vampire that harnesses it. When a vampire is in its Blood Lust state, it slowly begins to lose its senses of reason and logic, only operating as a wild and savage animal that will not only kill anything in sight, but will also kill its own kind and draining of them of blood.
Even vampires who claim to have mastered this form have difficulty of maintaining their senses and consciousness. Elder vampires like a Count or an Ancient are an exception to this as they had centuries worth of practice with this ability and thus are not subjected to the flaws of this power. The Blood Lust provides a vampire with increased strength, durability, regeneration, and speed. Which is enough for them to tackle even the more physically powerful werewolves. Not only that, but the vampires even have access to blood magic which can be used through the mist that envelopes them every time they are in Blood Lust mode.