1. Hold down shift (or whatever your walk key is) and walk into the wall for a couple of seconds (DO NOT RUN)
2. Pull out your swoop/mount etc. and while still holding down the shift key move forward into the wall.
3. You are in the wall and can go sf, shoot bounty marks etc. They won't be able to attack you because it'll say 'Cannot see target' but you can still attack them!
(Yes it's old but SOE still haven't fixed it and I couldn't see it in any of the exploit titles)