Source: Dragon #346
You weaken your foe's resistance to an energy type by warping his personal truename.
Prerequisite: Truespeak 12 ranks, any recitation feat, ability to speak utterances, must know your own personal truename.
Benefit: You lower a creature's energy resistances by 5 for 3 rounds by succeeding on a Truespeak check to say its personal truename. The Truespeak DC to use this denouncement is 5 higher than normal.
This feat does not grant you knowledge of a creature's resistances. It has no effect on creatures immune to an energy type rather than merely resistant. The reduction caused by this feat does not stack with itself, but you can use it multiple times on the same target to extend the duration of the reduction.