Instantaneous Rage

(Complete Warrior, page 102, DnD 3.5)

[General]

You activate your rage instantly.

Prerequisite

rage or frenzy ability

Benefit

Your rage begins at any time you wish, even when it's not your turn or when you're surprised. You can activate your rage as a free action in response to another's action. Thus, you can gain the benefits of rage in time to prevent or ameliorate an undesirable event. For example, you can choose to enter a rage when an enemy attacks you, or casts a spell at you (to gain the benefits of a higher Constitution or your bonus on Will saves) before you know the results of the attack. You must be aware of the attack, but you may be flat-footed.

Normal

You enter a rage only during your turn