In Russian vampire lore being born the son of a werewolf or witch is enough for a person to become a vampire upon death. Of this type of vampire, the myertovets, just about nothing is known of its abilities or hunting techniques. However, what is known about it is the very specific way in which it must be killed: a stake must be driven through its heart in a single blow. Should the stake miss or the strike was not powerful enough to penetrate all the way through, the vampire will immediately begin to kill its attacker.

Source: Bogatyrcv, Vampires in the Carpathians, 127, 171; Ronay, Truth about Dracula, 23; Summers, Werewolf in Lore and Legend, 15