“Behold! The inferno of destruction fills the heavens! Come forth! The Surge of Utnapishtim! This is what it means to destroy the World! Heroic Spirits, suffer the curse that the insolence of challenging the King of Heroes has brought upon ye!”
Sword of the End, Enki (終末剣エンキ, Shūmatsu-ken - Enki?) is the final weapon of Gilgamesh, a pair of golden twin blades that is stored within Bab-ilu and often worn on his back. Similar to Fate/stay night Gilgamesh's ultimate weapon, Ea, it is named after a Sumerian god, Enki. He uses them in close combat in conjunction with weapons fired from his vault with enough skill to equally battle King Arthur. They have the function to turn the hilts ninety degrees to allow them to be used as tonfa knives. The Gate of Babylon is shown to have identical swords in Fate/Extra CCC, though it is unknown if they possess the same name or abilities.
Differing from Ea, he has to meet a condition to unleash this imperial Noble Phantasm, and it takes most of his magical energy in order to utilize it. As a sword which can summon floods, it must be deployed for seven days as the volume in water increases each day after its activation. After the seventh day, it turns into the Surge of Utnapishtim (ナピュシュティムの大波, Napyushutaimu no Ōnami?) from the Epic of Gilgamesh, the original tsunami that gave shape to the deluge myth of Noah. Upon invoking its True Name, Enki takes the form of a longbow by connecting the two swords at their hilts. It generates an arrow that is fired at the ground to act as a "tracer round" for his true trump card that is deployed high in satellite orbit above the earth.
The actual Enki is surrounded by six bolts that converge around the sword in a spiral to become a spear that falls toward the Earth as a "Star of Destruction". Upon reaching the area, it disappears in the sky and deploys a giant Magic Circle that cleaves space to summon the Surge of Utnapishtim. The tsunami easily covers the entire city only seconds after emerging, and he implies that it has the capacity to destroy the world. Saber's Excalibur is able to win in a clash against it by splitting the water, vaporizing the sea, and cleaving the Star of Destruction.