Equestria welcomes a new stranger, though 'welcome' is a strong term. But it's not like they gave them much of a choice. That was fine, neither will she. The Mercenary W will prove them wrong.
The multiverse is just one grand experiment for many immortals as they try to explore its secrets. This is the story of one such experiment on what would happen if a new element was added to a universe that nearly exactly parallels the original.
Sombra was defeated, but his soul survived and traveled to a new world. He joins Ichigo and his friends as they invade Soul Society in an attempt to save another... while trying to remember his long forgotten past and who he really is.