What is "wamphyri"

Wamphyri are a form of vampire described by Brian Lumley in his Necroscope series.

Lumley has reinterpreted the traditional vampire legend. In his stories, a vampire is a leech-like parasite from an alien world which forms a symbiotic relationship with a host creature, usually a human or sometimes a canine such as a wolf or fox ( werewolf). While the symbiosis puts great demands on the host (such as requiring to feed on blood to survive), the benefits include increased strength, speed, and resilience, a seemingly infinite lifespan that stretches into millennia, magnified senses, base emotional stimulation, access to latent psychic power such as ESP or telepathy, metamorphic flesh allowing flight or disguise, and certain narcotic effects.

The vampires in the story have great control over people who are weak-minded, and could easily dominate the Earth if allowed to achieve their full potential. They also have the ability to produce lesser breeds of vampires for different purposes.