Vampire

The vampire has been a mystical being in Illaria for countless ages and has been represented as everything from a horrible monster carrying a deadly disease to pale, ever-living sexual devices in Emerald Era novels. However, these mystic qualities were earned by the individuals who were consumed with the disease, not the disease itself. Porus haemophilia, or quite literally "holes in the blood" is a disease that affects only those turned by way of a bite from another vampire or by drinking the blood of someone who carries the disease. The disease makes your immune system feeble (often making the infected allergic to even sunlight), and your thirst for blood insatiable. The benefits from such a disease are few, but some find the temptation of the grave too compelling.

For the price of your immunity to most forms of light, a sensitivity to silver, a hunger for blood -- human or otherwise, and distorted features like elongated fingers, the growth of fangs that crowd the mouth of otherwise healthy teeth, reddened or blood-tinged irises, and impotence (mostly in men affected) you would gain the following benefits:
 * Highly increased sensory perception, almost to the point of echolocation in the dark through the use of ears, night vision, enhanced smell, and sensitive touch that can feel minute vibrations.
 * Increased magical aptitude. As the holes in the infected linger, ethere begins to fill those voids. Some who contract the disease are actually given some measure of magical ability allowing them to perform feats that have been romantisied as belonging to all vampires such as shape shifting into bats or a swarm of bats, turning into mist, hypnotising with a glance, leaping great heights, running across flat surfaces like walls and ceilings, and a cadre of other so-called "vampiric powers."
 * In rare cases that the diseased person is able to survive his first full year after the disease has ravaged their body, the infected becomes biologically immortal. Their organs and other tissues stop aging, and their metabolic rates drop to near-death levels. This staves off their hunger for days or weeks at a time in some cases, allows them to enter a sleep-like trance to recover their energy faster, and go for long periods of time without breath under water or in enclosed spaces.