First enable #moveobjects then your Sim must say very loud to the golden knight:"For Luk the King and Simland!!" then scream to the silver knights: #SayNo2PublicShaming and now your Sim may enter the castle. Sir Eredin dosn't like other Sims. Only his Mom, lady Juliana and Luk the King, If your Sim plays chess and lets Sir Eredin win, it is possible that your Sim may stay alive. The chess table is on the west side (left, up, right, left, down left, up.. you'll find it, I hope, after 86 hours.