His Majesty the King of Heroes’ mobile air weapon. It uses solar energy, produced from a solar crystal that burns mercury as fuel, to move – a high-tech Indian Noble Phantasm that would make even Area 51 pale-faced. Even though in ancient Indian mythology, it also had weapons ranging from ancient machine guns to ancient nuclear warheads, these surely have already been gathered in the treasury of the King of Heroes.

Fate/Zero Material Encyclopedia: Vimana