Can someone please help me with a creative story?

will be having to write a creative story about this maze/citadel where there are 6 walls/ Information: The citadel is a huge fortress, with 6 huge walls, 1 within another . each wall has only 1 door leading inwards. Inside each wall is a terror protecting the centre against intruders. No one has got beyond tge 3rd wall before. First ring is protected by a rolling boulder. The door in the next wall is several hundred yards away. at the centre of the citadel is something you must have. You and 3 companions have come to get it. This is a world of magic powers and strange forces of dark and light. I was hoping for some ideas for each door like an obstacle for instance a big pile of keys and will have to find the correct key for the door. Each door gets harder and harder. could you guys please help!!! no rude comments please