Wikia

Energy vampires were creatures who drained the life forces of others, by way of biting their enemies in order to feed. They had retractable serrated claws, elongated teeth, accelerated senses, and enhanced strength and speed. They were able to drain beings of energy to feed as well as turning these beings into mindless zombies; when wounded, they could drain a being of energy to heal their wounds. However, they could still die from too much damage at once or from not healing their wounds fast enough. In rare cases, giving that the vampire had enough control, he could reverse the effect of feeding, and heal others by biting them. This would severely weaken him though. They were also in possession of long life, if not eternal.