Prometheus's punishment was to be chained to a rock and have an eagle (or a vulture by some variants) pick out his liver every day for eons, until Heracles slew the eagle, releasing Prometheus from his affliction.
Prometheus's punishment was to be chained to a rock and have an eagle (or a vulture by some versions) pluck out his liver every day for eons, until Heracles killed the eagle, freeing Prometheus from his torment.