Improved Natural Attack( Eberron Campaign Setting, p. 55)
One of a creature's natural attacks is more dangerous than its type and size would otherwise indicate.
base attack bonus +4, Natural weapon,
Choose one of the creature's natural attack forms. The damage of this natural weapon increases by one step, as if the creature's size had increased by one category. To determine the amount of the increase, fi nd the natural weapon's damage on one of the two progressions given below and improve it to the next higher die value. Progression 1: 1d2, 1d3, 1d4, 1d6, 1d8, 2d6, 3d6, 4d6, 6d6, 8d6, 12d6. Progression 2: 1d10, 2d8, 3d8, 4d8, 6d8, 8d8, 12d8.
A creature can gain this feat multiple times. Each time a creature takes the feat, the damage for a different one of its natural attacks increases. Special: A shifter may select Improved Natural Attack as a shifter feat. For a longtooth shifter, the damage his fangs deal increases from 1d6 to 1d8. For a razorclaw shifter, the damage his claws deal increases from 1d4 to 1d6.