Festival of Offerings
From Tardis Wiki, the free Doctor Who reference
The Festival of Offerings was a millennial ceremony on Akhaten. It was a system-wide event, with all those who had a belief in the beginnings of life being with Akhaten gathering to watch.
During the ceremony, the Queen of Years would sing the Long Song to feed the Old God, or "Grandfather," and keep him asleep. Then the Queen would be sacrificed to him, either willingly, or by the Vigil if she resisted. (TV: The Rings of Akhaten)
