Aura

"au·ra"
/ôrə/
noun
The distinctive atmosphere or quality that seems to surround and be generated by a person, thing, or place.

There are few creatures that possess the power to sense other being's auras. Those that do possess this power are referred to as an "Aruk" (air-rook). The Aruks have been feared for thousands of years, as some can not only sense a being's aura, they can manipulate it. Each of the Three Kingdoms had their own opinions of the Aruk.
To the first kingdom; the Kingdom of Elves, those possessing the gift of the Aruk were seen as a gift from the divine to rule their race, and were treated as royalty.
To the second kingdom, the Kingdom of Men, the Aruk were demons and anyone showing even a slight ability was either tortured, used as a weapon, or killed.
To the third Kingdom, the Kingdom of Morok, the Aruks were gods in the flesh. They were worshipped, and a Morok would do anything to protect their deities. Even if it meant killing their own kin.