User blog comment:Filheinz/Apocalypse............from the Shadow Isles?/@comment-94.243.244.60-20121231182047/@comment-112.210.27.78-20130101093312

You are probably referring to Karthus' old Lore, his new lore shows hi akkegiance to the Shadow Isles. As for Mordekaiser, I don't know, now that you mention it, he is thought to be "The First Undead" on the Isles.