Death Frenzy( Lords of Madness, p. 22)
When an aboleth takes this feat, its sense of immortality rebels against the very concept of death. If threatened with death, the creature becomes frenzied with speed and fury.
If the aboleth is reduced to fewer hit points than its total Hit Dice, it automatically enters a death frenzy. Entering this state is an immediate action; the aboleth can enter a death frenzy even when it's not its turn. While in a death frenzy, the aboleth cannot cast spells, use spell-like abilities, or use supernatural special attacks. When an aboleth enters a death frenzy, it gains a +4 morale bonus to its Strength and Dexterity, and the threat range for all its natural attacks doubles. When it makes a full attack, it can make one additional attack each round at its highest base attack bonus. Its land speed increases by 10 feet, and its swim speed increases by 20 feet. Finally, it gains fast healing 2. A death frenzy lasts until the creature is killed or until its hit points rise enough to equal or exceed its total number of Hit Dice. Upon emerging from a death frenzy, the creature immediately takes 1d4 points of Strength damage.