Battle with Purphoros
Heliod in his desire to establish himself as the leader of the pantheon, Heliod attempted to commission Purphoros to rebuild Nyx in Heliod's image. Angered by Heliod's claim to rulership, Purphoros forged the sword Godsend to fight Heliod.
As their conflict raged, Purphoros' sword cut the fabric of Nyx, opening the boundary between the realms of gods and mortals. As a result, the hydra Polukranos fell to the mortal world, but Heliod and Nylea joined forces to bind the hydra in the Nessian Wood.
Years later, the hydra broke free of its bonds, and Heliod chose a mortal, Elspeth Tirel, to slay the hydra as his champion—using a spear called Godsend, forged from Purphoros' sword.