You can fly into a berserk rage when injured.
Prerequisite: Wild shape ability.
Benefit: If you have taken damage during the last round, you may spend a wild shape as a free action on your turn to enter a rage. While in this rage, you gain a +2 bonus to Strength, a +2 bonus to Constitution, and take a –2 penalty to AC. This rage lasts for 5 rounds and cannot be ended voluntarily.
Source: Complete Divine, page 85.