Summary: This cheat is great for walking through towers and keeps without ever lighting them on fire to let the enemy know you are there. This cheat is not easy to learn and takes patients to understand the mechanics.
The Cheat: The way the cheat works is you are capable of walking through walls that have a cross wall of an angle equal to 89.999 or less. When you find your wall you want to try you face your body so your looking down the wall with either the wall you want to enter on the left of you or the right of you and about a 90 degree angel. In order for this trick to work you must have an obstruction on the wall you wish to enter.
Towers: The tower must be upgraded so it has the side door with the stairs on the side. You will use the stairs as your obstruction to enter. With your front of your characters body facing the steps, slowly line up your guy while autorunning so he is running to the corner where the tower wall meets the stairs. While auto running slowly turn your character to the right until you find that angle of less then 89.99 and you will see your guy slowly moving back and forth, but in towards the tower. If you are moving away from the tower you turned your guy to far. It will take awhile for your guy to enter the tower (30s-1min). Once he is alway the way in and will not move in further, stop your guy, turn in to the left so he is facing the stairs inside the tower. You must strafe to the left and move forward until you see your guy move deeper into the tower. At this point you can jump up in the tower and you are inside without taking down the door and can proceed to kill the lord. (I suggest not doing this with enemies inside, if a gm watches you do this you will get suspended).
Keeps: The same concept works for keeps. You can find points on the outside wall to walk through and get into the cy with the same method. (it varies for keeps and is not the same on all of them.). getting in the keep is harder then getting into the CK. You can get into the CK 100% of the time on any keep any level. (I used to kill bots inside the ck's and run out the top and jump out with my stealther). Again you must find the obstruction on the wall to enter. In the case of the CK's there is always 2 small obstructions on the back side of the ck. You can then use the method described for the towers to enter the ck.
Other: I have tried this same concept on just about everything. You can use this in poc to get behind the zone wall entrance and kill people entering and run away with out them being able to get you, or put a bot behind poc entrance and buff/spread heal yourself. You can use this exploit on enemy zone walls to enter their inner frontier. (works for alb and hib so far). Works on milegates. The possibilites of this cheat are as endless as your imagination of finding uses for it.