Polukranos

Polukranos, also known as World Eater, is a gigantic legendary Hydra native from Theros. First resting in a celestial lair, the monster fell to Theros because of the battle between Purphoros and Heliod. It was sealed in the Nessian forest by Heliod and Nylea. When the planeswalker Elspeth came back to Theros, Heliod made her his champion, and sent her to defeat the Hydra, which had awekened and was ravaging the lands. The monster fell, the Sun's chamion defeating it with Godsend, a swordspear crafted by Heliod using the same weapon who had made Polukranos fell from his former lair.