If you got Erika's amulet and she doesn't appear when you enter Rentar's great hall, then you made a mistake with the buttons in the basement. If you don't have a saved game that takes you back to the point where you start with the basement buttons, you can reset the buttons from Rentar's control panel by pressing the top left button. You will have to endure being teleported away from the control panel about five times before you can reach it. After you do that, I suggest saving the game and labelling it "Rentar's buttons" so you don't have to deal with all the teleporting if you make a mistake again.