Inaccurate?

Fiendish Resistance

( Complete Mage, p. 43)

[Heritage]

Your bloodline inures you against corrosion and fire.

Prerequisite

Fiendish Heritage (CM) , Non-good alignment,

Benefit

You gain resistance to acid and fire equal to three times the number of feats you have that list Fiendish Heritage as a prerequisite (including such feats that you take after gaining this one). These values stack with any resistance to acid or fire you might have from your type, subtype, race, or class, but not from other sources, such as spells or magic items.