Agile Hunter

Heroic Tier
Prerequisite: Dex 15, ranger, Hunter’s Quarry class feature
Benefit: When you score a critical hit with a melee attack against the target of your Hunter’s Quarry, you can shift as a free action, and the enemy takes a –2 penalty on attack rolls against you until the end of your next turn.

Published in Player's Handbook, page(s) 193.