Total Defeat
Drifting through the desolate upper atmosphere of Twyluxia, a behemoth of a bird strained against the extreme weather conditions at this elevation. However, it wasn't the void-like silence, the smothering darkness of space, or even the cosmic radiation and magnetic storms typical at these heights that made the flight perilous.
This world-plane wasn't a planet but a result of unique circumstances, making escape from this artificial prison impossible—even for Featherfall and its reputedly invincible rider.
Yet, in their current pickle, it wasn't the peculiarities of their world making high-altitude flight so dangerous, but a much more mundane issue: the thinning air. Lift relied on air density, just like Archimedes' principle, and the scarcer the air molecules, the more wing surface one needed to maintain altitude effortlessly.
The direct consequence? Despite its colossal size, the feared Titanic Beast struggled to maintain stable flight.