Mythril Engine - Final Fantasy XVI Database

In-game Description

The technology designed to propel the hideaway’s flagship, the Enterprise, across the seas at heretofore inconceivable speeds. It is not fueled by magic, but by mythril—a hard, inert substance refined from deadland soil. Inert, that is, unless burned at blistering temperatures, whence it releases all the energy stored within—for which reason, cooling is required in the form of a three-piece thermal displacement stack.