The quest being referenced is part of the "Kellos Invasion" questline, so you'll need to be up to date on that questline to start it! I'm not sure when the version you last played was, but we added in the quest "Immortal Kombat" back in the 0.41 release so you'll have to complete at least that quest before the Dark Wanderer will show up. If you've completed "Go for the Throat" already you can begin "Immortal Kombat" by ending the day, if you haven't then completing "Go for the Throat" should be all you need to start "Immortal Kombat"!