Tunnel Fighting( Races of Stone, p. 145)
You are adept at maneuvering and fi ghting in tight spaces and underground passages.
Base attack bonus +1,
You do not take a penalty on your attack rolls or to Armor Class when squeezing into or through a tight space.
A fi ghter may select Tunnel Fighting as one of his fi ghter bonus feats (see page 38 of the Player's Handbook).
Each movement into or through a narrow space counts as if it were 2 squares, and while squeezed in a narrow space a character takes a -4 penalty on attack rolls and a -4 penalty to AC. See page 148 of the Player's Handbook for more information on squeezing through tight spaces.