The Godsend is the swordspear that is wielded by Elspeth Tirel on Theros.
Once upon a time, when the God Purphoros raised arms against Heliod, he crafted the Sword of Chaos which was capable of damaging the substance of Nyx. When Heliod and Purphoros clashed, it damaged the celestial resting place of Polukranos, World Eater and the hydra fell to Theros where it was sealed by Nylea and Heliod under Nessian forest.
At the moment of the clash, Elspeth just had planeswalked to Theros for the first time. She saw the Sword of Chaos falling from the sky, grasped it and planeswalked away. When she returns to Theros, ten years later, Heliod is angry at her at first. But when the God realises she might be the Champion of the Sun reborn he reforges the sword into the Godsend. Elspeth uses her new weapon to defeat the awakened Polukranos.
Jouerneying into Nyx, Elspeth also defeats Xenagos, stabbing him with Godsend. But as a "reward", Heliod told her that no champion should know more than her god and because she knows and has seen places he does not know, he stabs her with the sword-spear, which shatters afterwards. Dying, Elpeth becomes confined to the Underworld of Erebos. A deathmask is forged for her, using the two jewels of Godsend.