Bloodwars (Necroscope #8)

The twin sons of Harry Keogh, the Necroscope, have taken very different paths. Nathan as his father's powers--to talk to the dead, to travel instantly through space. Like Harry, this new Necroscope fights evil wherever he finds it.

His twin, Nestor, has become the most horrifying evil imaginable: a shape-shifting, blood sucking Wamphyi Lord! Devoid of human feeling, Nestor and his companion, the beautiful, malevolent Wratha the Risen, hunt without mercy.

The battle between the brothers mirrors the war between vampires and humans. On mankind's side: terrible weapons brought from Earth by Nathan's allies. But the vampires are numerous and powerful, and neither side has a clear advantage...until Nathan and his legions of the dead discover a way to destroy the vampires forever.

In the midst of a titanic battle, Nathan makes a desperate move that forever changes millions of lives and two worlds: the vampire world...and earth.