Clever Opportunist( Drow of the Underdark, p. 47)
[Fighter Bonus Feat, General]
When an unwary opponent gives you an opportunity, you use it to change positions with your foe.
Combat Reflexes (PH) ,
If you hit a creature of your size or smaller with an attack of opportunity, you can spend an immediate action to exchange places with that creature.
Both you and the target must be able to move into and legally occupy the new space in order for this feat to function. For example, an incorporeal character inside a solid object couldn't exchange places
with a corporeal character, nor could a nonflying creature exchange places with an airborne flying creature.
A fighter can select Clever Opportunist as a fighter bonus feat.