The Shadow Isles, the Ruined King, and Kalista
I wonder.
Kalista has several quotes when buying Blade of the Ruined King: "Once, he was a noble king, until grief overcame his reason." "In the end, it was not his blade that stole our lives."
Which made me think- Maybe the reason the Ruined King broke the barrier between Life and Death was not to forge an army of undead, but to bring back a loved one? And maybe Mordekaiser, who is "a being of pure, living agony on a mysterious dread quest" was sent to find out how to break the barrier? Maybe it went horribly wrong and the Shadow Isles became what we know them today?