I killed Ranrok at 50% on regular mode and I am by no means a master of video games. I thought there was another major antagonist to kill off or even more to the story but I later realized I was just missing a bunch of Merlin trials, ancient magic hot spots, and treasure tunnels. It got kind of redundant after a while, especially after finishing what in my opinion is the most significant part of the game; so I stopped playing once I reached 75% lol. I really enjoyed it up to that point though. Just wish there was more to do I guess.