The Titans

"Destroy him!"

The Titans answering Hades' question of what they will do to Zeus

The Titans are massive beasts that were trapped by Zeus a millennia ago. Their cage resembled a criss-cross of lightning bolts, 2 across and 2 down. It was also created on the ocean floor. The only way to release them is every 18 years when all the planets align, and creates a large enemy beam that allows the user to destroy the lightning bolts. There is also a cyclops, but for some reason it is excluded from the beginning scene, implying that it was less important and therefore removed.