Your skin is thickened with the strength of stone.
Prerequisites
Giant Bloodline (Stone Giant), bloodline level 1st.
Benefit
Your natural armor increases by 1. In addition, once per day, you can cast stoneskin (self only) as a spell-like ability with a caster level equal to your bloodline level.
You can use this spell-like ability one additional time per day for every four Gigantic feats you possess, including this one.