Since you can now pass through npcs you can walk on top of them and stay there. If you do this to a mob that is attacking you and is ranged it will no longer move away trying to gain a range advantage like if you were just 1 square away. Also if you do this against dragon and he does flame breath to ignite the square your on, he actually takes damage from his own spell (although hes nearly resistant to it and takes very little damage).

 

Oh and no clue if this is a bug but ranged mobs don't take damage back if they hit a piece of armor with feedback/current/etc.