He comes from the Void

Kane, who started with Scourge, crossed to the most dangerous corner of Runeterra-Lost Icathia. In the dark underground, people are inaccessible and wild beasts are rampant. If it weren’t for the girl who turned into a monster, Kane might have become the shortest-lived traverser in history. To survive, he had to hug Kai’Sa’s thigh tightly. But he couldn’t eat soft rice all the time. He began to reproduce the medical miracle that happened to Kai’Sa, risking his life and actively accepting the void, wanting to give himself a symbiotic void armor. But what he didn’t expect was that the moment he did it, Void is scared… ---- Finally, I found the Runeterra fanfic, you found it in MTL just search the title...