Eldritch Mark( Dragonmarked, p. 139)
You channel the power of your dragonmark into your eldritch blast.
Ability to invoke an eldritch blast, any true or aberrant dragonmark.,
When you hit a creature with your eldritch blast (Complete Arcane 7), you can spend 1 action point to disorient the target, forcing it to succeed on a Fortitude save or become flat-footed. The DC of the save is 10 + your level in either the dragonmark heir prestige class or the heir of Siberys prestige class + your Cha modifier.
Note: A creature with the Mark of Stars feat (page 142) is immune to the effect of Eldritch Mark.