Two brothers began a war, and now it's coming to an end. Urza and Mishra were the brightest artificers and archeologists of their time, discovering great wonders from the ancient Thran empire. When they uncovered an ancient powerstone, however, their differences became hatred, and war began to build between them. Unknown to Urza, Mishra made a pact with the Phyrexians, an ancient enemy of Dominaria, during the war and allowed them to augment his power. During the climatic battle of the Brothers' War, Urza learned that Mishra was now merely a construct of flesh and phyrexian metal. When Urza and Mishra confronted each other, Urza was forced to release a cataclysmic burst of energy, destroying Mishra, leveling the magnificent forest of Argoth, and transforming himself into a planeswalker.
After the Brothers' War ended, and as the climate cooled as a result of the magical energies released at the war's end, Dominaria endured a series of hardships. On the northern continent, religious zealots hunted any who practiced magic. On the southern continent, the cooling climate hampered the resources of the dominant cultures, and one by one, the great empires of Sarpadia fell. An ice age came and went, and all the while, the people of Dominaria struggled to survive.
Unknown to most of Dominaria's beleaguered inhabitants, Urza had begun travelling the planes. Still unable to fully understand his own transformation and the tragic events on Argoth, Urza focused on the beings responsible for his brother's transformation, the Phyrexians. Once he discovered the phyrexian plane, Urza found himself overmatched by the phyrexian forces, and he quickly retreated. While Urza recovered from his disastrous first foray into Phyrexia, he began to design a way to fight them. As powerful as he was, Urza knew that the phyrexian horde was all but unstoppable, and he knew that he would need to find a way to defeat their planned conquest of Dominaria. He discovered that the phyrexians had tried to invade Dominaria once before, only to be repulsed by an ancient empire called the Thran. Heartened by this knowledge, Urza began to explore means of traveling through time to learn the secrets of the Thran. Although the academy on Tolaria produced many wonders of artifice, the experiments with time ultimately brought only chaos and failure. Abandoning his attempts to travel to the Thran civilization, Urza turned to Thran technology available in his own time. After discovering the Shivan mana rig, he hit upon a plan. He envisioned a weapon of great power, made of artifice, a living focus, and pure magical energy.
He began building the Legacy.
He worked in Shiv to get the Thran metal and the powerstones he needed. He journeyed to Yavimaya to get the living wood he needed. And finally, he assembled the Weatherlight, the flying ship that is the most visible part of the Legacy artifacts. With his work on the artifacts of the Legacy well underway, he now needed only the human component, an area where his skills were lacking. Urza began manipulating the bloodlines in several regions of Dominaria.
Two thousand years later, the Weatherlight was in the hands of a capable crew, led by Captain Sisay. The downside: Sisay had just been captured by Volrath, the evil Evincar of Rath. Gerrard, reluctant heir to the Legacy and unknowing product of Urza's experiments, lead the crew in Sisay's absence, struggling to save Sisay and keep the crew together.
Gerrard and the crew of the Weatherlight journeyed across the artificial plane of Rath, not knowing that the plane itself was one of the most crucial parts of the phyrexian invasion plans. Their journey ended at the Stronghold, the seat of Rath's tyrannical government and home to Volrath, one of Yawgmoth's most dangerous servants. The heroes of the Weatherlight managed to rescue Sisay and escape Rath.
Fleeing Rath, the Weatherlight was stranded on the mercantile plane of Mercadia, and the crew was forced to barter with the double-dealing denizens of the plane in order to repair the Weatherlight and get back to Dominaria.
On Rath, Crovax, formerly a member of the Weatherlight crew, turned completely to evil, becoming the new evincar and one of Yawgmoth's most brutal servants. The forces of good were not left without hope however. Two new champions arose to lead the good races of Rath against the forces of the Stronghold. Eladamri, leader of the elves, and Lin Sivvi, leader of the human rebels, fought against Crovax's oppression and eventually followed their destiny to Dominaria, becoming important warriors for good throughout the war with phyrexia.
As the last parts of his plan came together, Urza assumed the guise of a blind seer. Travelling with the Weatherlight , he guided the crew through the last steps of their journey. The Weatherlight streaked briefly through Rath, only to find it filled with massive amounts of phyrexian troops and portal ships. The Weatherlight sped through a portal, destroying thousands of phyrexian troops in the process. The triumph was short lived, however, as the crew found the sky above Benalia filled with phyrexian shock troops.
The invasion had begun.
The first battle was fought over Benalia. The Weatherlight streaked through the skies, faster and more maneuverable than the huge invasion ships, it wrecked havoc on the phyrexian fleet. But the phyrexians had come in force, and one flying ship wasn't enough to stem the onslaught. The Belanlish forces fought valiantly, but the legions of phyrexia would not be stopped, and they quickly overran the defenses. Even though Urza and Barrin lent their magical strength to the conflict, phyrexia quickly established a foothold on Dominaria.
All of Dominaria was besieged, but the struggle revolved around three key battles: the metathran trying to destroy the portal at Kolios and the defense of the two sentient forests, Yavimaya and Llanowar. Despite tremendous losses, the Coalition, Dominaria's defenders, drove the phyrexians back, and at Kolios, they managed to destroy the portal to phyrexia.
The Coalition victory was short lived however, as huge portions of the artificial plane Rath began to overlay themselves onto Dominaria, bringing hundreds of thousands of phyrexian shock troops along in the process. Their victory forgotten, the Coalition forces hurled their might at the Stronghold, now overlaid onto the swamps of Urborg. They fought, and fought well, and Urza Planeswalker lead a powerful group of planeswalkers to Phyrexia itself, hoping to destroy the invaders in their home. Yawgmoth's forces were not to be easily defeated though, and the dark god laid plans to trap Dominaria's most powerful defenders.
The final chapter begins with Urza and Gerrard trapped in Phyrexia, forced to endure the whims of the dark god Yawgmoth. Gerrard and Urza are forced to fight each other in an arena, and when one kills the other, the loser is returned to life by Yawgmoth's power and the two must fight again. Eventually, Gerrard wins free, only to find himself in the Stronghold throne room, with a crazed Crovax standing over the broken form of Squee, the Weatherlight's cabin boy.
The Sisay, Karn, Tahngarth, and the rest of the Weatherlight crew desperately search the Thran Tome, attempting to figure out how the Legacy and the Weatherlight are supposed to save Dominaria. The remaining coalition forces, lead by Grizzlegrom, Eladamri, and Lin Sivvi fight their way to the Stronghold, where they battle Crovax's phyrexian soldiers. Although they hold their own in the battle, the coalition forces are unable to find a way into the Stronghold.
Back inside the fortress, Gerrard finds his way out of the Stronghold, but then, things get worse. Yawgmoth himself steps through the portal from Phyrexia. The heroes regroup on the Weatherlight, and the final battle begins in earnest. Can the the Legacy save Dominaria now that Yawgmoth has moved his full power to the plane? Will there be anything worth saving after the battle is over?