Leaf on the wind is an encounter power available to warlords at 1st level.
The "Class Compendium: Warlord" article in Dragon 397 changed the movement effect of leaf on the wind to require a free action.
CharOp Evaluation: Poor [Charop Warlord]
Generally, swapping places with an opponent is of negligible tactical significance, meaning most of the time, this ends up being just a slightly more damaging basic attack.