This flighty avian wonder is possibly the most important character of the entire Chronicles, and has inspired a wealth of fan art and stories about its heroic deeds.
The three-winged bird was resurrected by a random flash of wild magic from Covenant's ring, which first ricocheted off the Illearth Stone, was then swallowed by a curious Ur-vile, passed through its digestive system and out of the other end, also becoming briefly lodged in Infelice's left nostril during its fantastic journey through time and space. Hence this spark intensified in strength, imbued by various flavors of Landish powers, and thus was later able to baptize the born-again bird with several eldritch qualities, including preternatural vision.
After many a wondrous adventure, the accounts of which can be discovered in a spin-off series called "The First to Fourth Chronicles of the Three-Winged Bird" (currently comprising 25 books) it soared to the far-off realm of Angry Birds to learn advanced warcraft. Later, it spent eons building a durable slingshot that would increase its speed, while the third wing provided it with extra aerodynamic balance whilst targeting particularly tricky-to-get-at pigs.
However. the ultimate purpose of this plumed protagonist was revealed when the Worm wished to gobble the Land for breakfast in The Last Dark. While Linden & co. bumbled around in the gloom, tottering in circles and colliding with one another, the bird launched itself into the air, zoomed straight into the Worm's gullet, and sacrificed itself for the greater good. The power roiling within its feathers functioned akin to an efficient sleeping pill: soon the Worm became drowsy and wormed its way back to the Earth's core. Thus the Land was saved from utter perdition, even though everyone had to learn to cope without a proper sun thereafter.