Coatls
Coatls are a species of serpent-like xenoforms, who the Aztecs worshipped as gods. They included Quetzlcoatl, Coatlicue, Cihuacoatl, Mixcoatl and Xiuhcoatl.
The blood of coatls carries their power. Gifted to a mortal via transfusion, it grants strength, speed, immortalty and supernatural powers. Tezcatlipoca stole a quantity of Quetzalcoatl's blood long ago.