When Pelias shoots his beam at you, block until it ends. Then, shoot him with a spear. Repeat this twice. When Pelias flies around and shoots purple flying balls at you, hold [Block]. Wait until the balls circle you, then press [Power Block]. When Pelias stands on the ground shooting purple balls, stand near him, and keep tapping [Power Block]. You should not take any damage.
Rise Of The Argonauts