Nephilim are a supernatural race of half angels and half humans. They are created when an angel impregnates a human woman. All Nephilim appear completely human and generally, don't possess any great moral obligation to good, naturally. The Nephilim were the offspring of the "sons of God" and the "daughters of men" before the Deluge. Nephilim, in the Hebrew Bible, a group of mysterious beings or people of unusually large size and strength who lived both before and after the Flood. The Nephilim are referenced in Genesis and Numbers and are possibly referred to in Ezekiel. The Hebrew word nefilim is sometimes directly translated as “giants” or taken to mean “the fallen ones” (from the Hebrew naphal, “to fall”), but the identity of the Nephilim is debated by scholars.
The Nephilim are portrayed as tall, muscular demigods capable of incredible power, such as shapeshifting into giant demons and possessing incredible advanced weaponry.
Longevity - Nephilim have a slower aging process and while they will die eventually, a nephilim can live up to five hundred years, although most of them never make it that far, considering how often they're hunted.
Regeneration - Nephilim heal from most injuries within seconds of being hurt. With the exception of weapons being dipped in holy water or being burned in holy fire.
Extrasensory Perception - All nephilim, like many other supernatural races are able to sense other supernaturals nearby, feeling their power as if through a strange headache. However, this sense does not give them the knowledge of what they're sensing. Each supernatural race has it's own "feeling", and if a nephilim has sensed that race before, they will most likely recognize it. If they haven't, then all they know is that the person is supernatural, not what they are exactly.
Super Strength - Nephilim are capable of feats of strength that rival even some vampires. A nephilim will grow stronger, and unlike most other races that possess super strength, can "work-out" to improve their strength. Though what a nephilim needs to use to get stronger are considerably different than what a human needs.
Invulnerability - Nephilim are naturally more durable and more resilient than an average human. While they can still be shot by a bullet, something like being hit it in the head in an attempt to knock them out will probably not work.
Heaven’s Enmity - Angels regard nephilim as the worst kind of abominations, more detestable than even demons and devils. An angel will always react negatively to a nephilim, and will always interpret the angel’s words and actions in the worst possible light. Nephilim can never benefit from healing or other miracles from angels. While hunting nephilim is not a perrogative of angels, many do not think twice about smiting a nephilim if they come across one. Nephilim are in no way held in any regard by angels, and thus no angel will look down on another for killing a nephilim.
Lamb's blood - Angels and nephilim are incapable of crossing a line drawn in lamb's blood. Additionally, any weapon soaked in lamb's blood can inflict a wound on a nephilim that will only heal as fast as a human's wound would.
Hellfire - While very rare, a ritual can be used to create a type of brimstone that when lit, burns what is known as "hellfire". This magical fire acts like kyptonite for angels and nephilims alike. For angels, it can be used to evict them from their host, and for nephilims, it temporarily stips them of all their powers.