Great Mending

The Great Mending (or just the Mending) was a process that healed Dominaria from the damage caused by the time rifts through the sacrifice of multiple planeswalkers.

It began when Jeska sealed the last major rift in Otaria in 4500 AR. It caused all remaining fractures to heal, first in Dominaria but then spreading throughout the Multiverse in a chain reaction. The Mending allowed mana to flow freely throughout Dominaria once more, returning life and hope to the dying world. All creatures which had appeared from the past during the Time Spiral crisis returned to their original time. With the last Time Rift closed, Dominaria's mana flowed back into the land instantaneously, and the world healed and rejuvenated quickly with that infusion of power.

After the Mending, the Multiverse found a new balance with the Planeswalker's spark, with far reaching consequences. Planeswalkers lost their immortality and godlike powers and much of their additional magic power. For example, they stopped being able to transport other people during a planeswalk. At the same time, all existing planar travel tech also stopped working. New tech was possible, but so far the only example seen is the Planar Bridge created by Rashmi on Kaladesh, which has notable limitations regarding organic matter.

The Mending occurred about 60 years before the present (4500 AR). Remarkably, this is around the same time that the Great Aether Boom of Kaladesh occurred.