Needs review
Source: Player's Handbook

Description: You are skilled in mounted Combat

Prerequisites: Ride (1 rank)

Required for: Aerial Mounted Combat, Improved Mounted Archery, Legacy of the Four Winds, Mounted Archery, Ride-By Attack, Tunnel Riding, Way of the Ox

Once per round when your mount is hit in combat, you may attempt a Ride check (as a reaction) to negate the hit. The hit is negated if your Ride check result is greater than the opponent's attack roll. (Essentially, the Ride check result becomes the mount's Armor Class if it's higher than the mount's regular AC.)

Special

A fighter may select Mounted Combat as one of his fighter bonus feats.