Requirements: Something that can protect you from the trains, an Overshield will help.
Process: When you get to one of the train tracks that lead to a tunnel, you will not be able to enter. Wait on the track that one of the trains go out on, and stand with your back to the tunnel so you cannot go backwards anymore. the train will come and push you through all the way. you will not be able to get out though. To get out, do the same with the other train. This will usually push you out of the map and kill you. The inside of the tunnel is perfect for swords matches in slayer. You can snipe other players and be safe since they cannot get in to kill you.