Earth Lore (3.5e Feat)
From D&D Wiki
Earth Lore [Racial]
Dwarven spell casters have a connection with the natural stone of there homeworld that powers their spells.
Prerequisite: Dwarf, arcane spellcaster level 3rd
Benefit: You gain a +1 bonus on the save DC of your arcane spells if you are standing on natural rock or earth.