Keres

"Die in pain, mortal!"

- Keres

The Keres (in Ancient Greek: Κήρες, also known as Daemones) are battlefield spirits of famine and disease that feed on violent death and are polluting spirits. The Keres were daughters of the Protogenoi Nyx. In mythology, they were found wandering battlefields. In later times they were regarded as the vengeful spirits of the dead. They are the opposite of Thanatos. They live in the Underworld and supported the Titans, but didn't directly attack Olympus in the Second Olympian War.

The Sword of Hades
Percy, Thalia, and Nico are ambushed by a group of Keres. During the battle Percy is poisoned by one of them, and would have died if Iapetus did not heal him, who has his memory erased. They poison enemies by scratching and injecting their poison into the bloodstream. On Percy, they scratch him on his exposed shoulder.

Description
During the battle Percy describes them as part humanoid females, part bats; with pug-nosed and furry faces, fangs, bulging eyes, shriveled arms, claws, leathery wings, and stubby bowed legs

Abilities

 * Keres feed on death, which means their power increases when people die.
 * They have deadly poison that only the power of a god or Titan can heal.