Lorwyn is an idyllic, storybook world where races of fable thrive in perpetual midsummer. The plane is covered with dense forests, meandering rivers, and gently rolling meadows. The sun never quite dips below the horizon, and winter is entirely unknown.
That's not to say Lorwyn is without conflict. Its races have their struggles and skirmishes, some isolated, some long-standing. Lorwyn is one of the few planes without humans, but many other races fill in the gap. In the outlying town of Burrenton, for example, the short-statured kithkin face the encroachment of a nearby flamekin settlement. The flamekin are the race perhaps least at home in sunny Lorwyn. Their natural fires are a threat to others who are suspicious of their impulsive natures and hot tempers.
Far away in the Porringer Valley, gangs of boggarts sneak in amid groves of treefolk to make trouble and steal "souvenirs" of their trespasses. The boggarts are greedy for sensation, always seeking out new tastes, smells, and experiences. Each boggart warren visits others for their "footbottom feasts," a chance to share the experiences accumulated by other warrens.
As these squabbles continue, the merrows, the merfolk of Lorwyn's rivers, act as diplomats, couriers, and merchants for the other races. They use underground channels and wells as conduits for communication, and because the merrows are intelligent and kind, they usually end up getting the better end of the deal.
If the merrows are Lorwyn's merchants, the giants are its arbiters and advisors. The iconoclastic, territorial giants wander Lorwyn according to their own whims, only occasionally stopping to address the concerns or complaints of the little folk. The rest of the time they sleep or bicker among themselves.
Of all Lorwyn's denizens, though, the elves are both most favored and most feared. In a world of unspoiled nature and lush forest, the elves believe themselves to be the paragons of natural beauty. Signs of elvish supremacy are widespread in this world, from their gilded forest palaces to their mercilessness toward the other, "lesser" races. Despite the elves' domination, Lorwyn's people thrive through community and tradition, and perhaps with some help from an unseen power.
Faeries are ubiquitous in Lorwyn, like bees gathering pollen. Although the capricious and mischievous creatures seem to behave unpredictably, all are guided by the will of Oona, the queen of the fae. Oona's magic is said to keep Lorwyn in its midsummer state, but few have ever seen her. Her throne, Glen Elendra, is a half-mythical place that few but the fae have ever seen.
Lorwyn is ancient and verdant, and its natural processes are locked in familiar cycles. For instance, every year for countless decades, the kithkin town of Kinsbaile has hosted the Festival of Tales, a gathering to tell stories and make merry before the Aurora, an annually occurring display of lights in the sunset sky. But some auroras are greater than others. On a long cycle that only the faerie queen Oona comprehends, an aurora can bring about a total transformation of the plane of Lorwyn. Afterward, what remains is the plane of Shadowmoor, a realm of eternal dusk.
Shadowmoor is a plane of perpetual dusk where the sun never rises, and where strange light seems to come from unseen sources. This plane is Lorwyn's opposite. Lorwyn is an idyllic midsummer, but Shadowmoor is trapped in a state of crepuscular gloom. Lorwyn's races skirmish over territory and property, but Shadowmoor's races are locked in a perpetual, life-and-death struggle for survival.
Like Lorwyn, Shadowmoor is devoid of humans. Lorwyn's many other races, however, persist in Shadowmoor...but like the plane itself, they too are transformed into darker versions of themselves.
The kithkin, once communal and cooperative, are isolated and xenophobic in Shadowmoor. They live within walled towns, shunning outsiders and attacking those who get too close. The once silver-tongued merrows are assassins and saboteurs in Shadowmoor. They use the waterways to move quickly from victim to victim, always ready to drown and loot land-dwellers. Likewise the boggarts, once mischievous and hedonistic, are in Shadowmoor vicious and warlike. Their interests have turned from curiosity to pillage, and from stealing pies to stealing babies.
The larger denizens of the world, the giants and treefolk, find themselves changed as well. The treefolk of Shadowmoor are blackened, blighted, murderous creatures. And when awakened from the long hibernations, the giants are terrible, wrathful beings that carry huge pieces of the land itself on their bodies.
The transformation of the flamekin is perhaps the most dramatic—and tragic. Once their fires burned bright, but now they are extinguished, reduced to skeletal, smoking husks called the cinders. In Lorwyn they sought emotional transcendence, but in Shadowmoor they seek only to satisfy their malevolence and need for revenge.
The imperious and vain elves of Lorwyn find themselves humbled but heroic in Shadowmoor. Whereas Lorwyn's elves sought to judge and subjugate others, Shadowmoor's elves are the world's last hope—seekers and protectors of beauty and light in a dark, ugly place.
Only one race and one place remain unchanged when the Great Aurora turns Lorwyn into Shadowmoor: the faeries and their home of Glen Elendra. The fae are the fulcrum of this transforming plane, for it was their queen, Oona, who created the Aurora.
There was a time when Lorwyn had annual seasons and was "in balance." It was Oona who sought more influence and control over the world. From her secret glen, she wove countless powerful spells into a web of magic that would grant her more power over Lorwyn. But as Oona's enchantments on the plane grew more complex, the world was thrown out of balance. The very nature of the plane's denizens, objects, and places began to split; they developed "Jekyll and Hyde" existences.
Rather than risk losing her control of Lorwyn, Oona created ever more powerful glamers to stabilize the plane. Eventually she accomplished her goal. Lorwyn's fluctuating states fell into a regular interval of long, bright, warm summers, and long, dim, creepy autumns. The costs to the plane were substantial, however. First, each interval lasted for almost three centuries. Second, on each change from the Lorwyn to Shadowmoor state, the plane's denizens lost all awareness of their previous existence.