Source: Dragon #346
You can mask allies by warping your foe's truename.
Prerequisite: Truespeak 12 ranks, any recitation feat, ability to speak utterances, must know your own personal truename.
Benefit: As an immediate action on a foe's turn, you can designate one of your allies as someone your foe cannot attack with melee or ranged attacks until the end of his turn. This only affects the foe's ability to make attacks for the rest the round. You can choose to use this ability in the middle of a foe's turn, even in the middle of a full attack action (and even if he already attacked the designated ally). You can designate yourself as an ignored target. You must succeed on a Truespeak check to say your foe's personal truename. The Truespeak DC to use this denouncement is 10 higher than normal.
You can only choose a specific combination of attacker and protected target three times per encounter, but you may choose any particular attacker or protected target at will.