Aqua Mortis is a rare alchemical substance described in the Kitab al-Azif — the Arabic text better known in Western occultism as the Necronomicon — and required as a component in the ritual H-Cell is preparing to use against Das Ungerhauer. It is produced by passing mercury through aged copper pipe, mixing with methyl sulfide in a stone or ceramic vessel, adding dust from a virgin's bedsheets whilst stirring counterclockwise, and finally incorporating grave water drop by drop whilst reciting a dissolution incantation. The substance must be allowed to settle until it ceases moving of its own accord.
The cell sourced the grave water from Omar's cousin's bazaar in Cairo — a luminescent liquid drawn from tombs thousands of years old — and obtained appropriately aged copper pipe from a local coppersmith rather than the military depot, with Hanover instinctively recognising the verdigris-covered old pipe as superior to virgin copper. The complete ritual requires precise timing: the mercury must be passed through the copper three times under different conditions (daylight with incantation, candlelight in silence, open starlight between 2300 and 0015), with the full process conducted overnight before departure.