From Compendium of Worldly Lore
Needs review
Source: Races of Stone
Description: You are adept at fighting on the uneven ground of mountainous terrain.
Prerequisites: Wilderness Lore (5 ranks), Base Attack Bonus +3
When you make a melee attack from higher ground than your opponent, you gain a +1 bonus on your damage roll. When you make a ranged attack from higher ground than your target, you gain a +1 bonus on your attack roll. When an opponent attacks you in melee from higher ground, the opponent does not gain a +1 bonus on its attack roll. You gain a +2 bonus on all Balance checks made when moving on steep slopes.
Special
A fighter may select Mountain Warrior as one of his fighter bonus feats.
Normal
A character who makes melee attacks from higher ground gains a +1 bonus on attack rolls. Ranged attacks made from higher ground do not receive any bonus.