The Ancient Magus' Bride: The Boy from the West and the Knight of the Blue Storm

Every few decades, the Wild Hunt, a group of mounted fae knights, wakes and roams the land, its presence causing old plants to wither and letting new ones take their place. Unfortunately, when lightning strikes the stone monument where the Wild Hunt sleeps, it chips off a fragment containing the band's guide. As a result, when the Wild Hunt rises again, its members cannot hold their formation, instead wandering the forests aimlessly and leaving death behind them. In an attempt to fix this, Spriggan tasks Elias Ainsworth with bringing the missing guide's steed back to its master. Meanwhile, Gabriel, an asthmatic young boy who longs for adventure, finds the chipped-off rock and ends up summoning the knight inside. With his only intact memory being the wish to return, the guide must reunite with his steed and his pack before his absence causes irreparable damage.