well, i was shown this on the test server (PVE) for patch 1.11, so it might not work on the regular servers, and it might. (ive been so busy, and all bro does is play on test server, soo ill check into it). But the does work on test server. Face the bank in IF. u kno those lil corridors to the left or right of it? go to the left one. Facing as if u would go down the corridor and appear in the great forge hug the right wall. go all the way to the end right beside the great forge. Now just face against the wall at the smallest possible angle so u just move to the side a very lil bit (make the angle twords the bank end of the corridor (where u came from)) Then run. RUN RUN RUN. If ur angle is small enough u will be going in the wall. and u will fall through the wall into old if!!!!! (it may be a lil fustrating, but once u get u r in alive and well!!)
The only hard part is to make the angle small enough so ull go through the wall b4 u hit the first toch which will mess up the process
have fun and amaze ur friends!!