fountain of blood (dominions)

One of the possible Pretender Gods in the game series Dominions:
"The Fountain of Blood is a horrible spirit that inhabits an unholy fountain that spews forth blood instead of water. The spirit possesses a girl to serve as its instrument. The chosen child is blinded and rendered unable to do anything but speak the will of the spirit. At the age of thirteen, she is sacrificed and replaced with a new girl, born the day the previous girl was made the voice of the spirit."