Rayden- Beat Konquest first, then go the the Orderrealm area E-3 and fight him, win and he gives you the key.
Liu-kang-Go to Edenia and do Rain's mission. then go to Jade's tent in area G-8 (look on map it's a trail on the far right side of the map. she will instruct you on the mission. then when you finish the mission, go behind Jade's tend, the outside of it. it must be 12:00am Friday (meditate if needed) but the midnight bell must ring. you have 30 seconds to open it when it appears. at the back of the tent, look at the right side it will be there.

Where Is Raiden,He Isn't On E3!!!