When you obtain Greater Charisma, Intelligence or Wisdom V-feat you will get a DC buff of +1 to ALL spells.
It will progress with one for every next feat beyond that to a maximum of +6 at Greater **** X.
There is a check to make sure it will only work if the caster is not multiclassed. If the caster is multiclassed with pale master, then he will only get a DC bonus to his necromancy spells.