|Title:||Key of the King's Law|
Bab-ilu: Key of the King's Law (王律鍵, Ōritsu Kagi?) is a tattoo that proves the kingship of Gilgamesh and acts as a key to access his treasury. It shares the same functionality as Fate/stay night Gilgamesh's Gate of Babylon and the name of the key-sword that unlocks it. It allows him to draw out weapons like Enki for personal use and fire an endless barrage of swords at enemies like a machine gun. Differing from the Gate of Babylon's ability to manifest them from ripples anywhere, Bab-ilu has a circular pattern of ten glowing orbs that appears around him. While the Gate of Babylon is generally used from a standing, long range position, Gilgamesh utilizes Bab-ilu while rapidly moving around and engaging in melee combat with Enki. He comments that it contains many pointless things, such as a glass bottle containing a medicine that can cure any poison in the world.