You can fly into a rage a certain number of times per day.
In a rage, you temporarily gain a +4 bonus to Strength, a +4 bonus to Constitution, and a +2 morale bonus on Will saves, but you takes a –2 penalty to Armor Class. The increase in Constitution increases your hit points by 2 points per level, but these hit points go away at the end of the rage when your Constitution score drops back to normal. (These extra hit points are not lost first the way temporary hit points are.) While raging, you cannot use any Charisma-, Dexterity-, or Intelligence-based skills (except for Balance, Escape Artist, Intimidate, and Ride), the Concentration skill, or any abilities that require patience or concentration, nor can you cast spells or activate magic items that require a command word, a spell trigger (such as a wand), or spell completion (such as a scroll) to function. You can use any feat you have except Combat Expertise, item creation feats, and metamagic feats. A fit of rage lasts for a number of rounds equal to 3 + the character’s (newly improved) Constitution modifier. You may prematurely end your rage. At the end of the rage, you lose the rage modifiers and restrictions and become fatigued (–2 penalty to Strength, –2 penalty to Dexterity, can’t charge or run) for the duration of the current encounter.
You can fly into a rage only once per encounter. You can use your rage ability once per day. Entering a rage takes no time itself, but you can do it only during you action, not in response to someone else’s action.
You can take this feat multiple times, once every four character levels. Each time you take this feat, you can use it one additional time per day.