You can channel energy to infuse your skin with the strength of the earth.
Prerequisites: Con 13, Wis 13, Earth Sense, ability to rebuke earth creatures
Benefit: As a standard action, spend one of your rebuke earth creatures attempts to increase your natural armor bonus by 2. This increase lasts for a number of minutes equal to your Constitution bonus.
Special: You must be touching the ground to use this feat.
Source: Races of Stone, page 139.