Combat Acrobat( Player's Handbook II, p. 76)
[Fighter Bonus Feat, General]
Your acrobatics and agility in combat allow you to maneuver across the battlefield with ease. You stay on your feet and speed over difficult terrain due to your superior athleticism and acrobatic talents.
You gain several benefits from this feat to reflect your overall athletic ability and training in the skills vital to an acrobat. Acrobatic Recovery: If an effect causes you to fall prone, you can make a DC 20 Balance check to remain on your feet. Sure Footed Maneuver: With a DC 15 Balance check, you can ignore up to 4 squares of difficult terrain while moving. You treat these squares as normal terrain. You still endure any effects or hazards associated with the terrain. For example, a shallow pool of boiling water might deal fire damage and count as difficult terrain. You would still take damage from the water even if your Balance check allowed you to move through it at full speed.
A fighter can select Combat Acrobat as one of his fighter bonus feats.