I noticed that Wail of the Fallen, despite (presumably) being a 1x a day ability and requiring 3 levels into a PrC, has a pretty easy DC.
The only possible DCs are 11, and then a level later it raises to 12. The way the DC is calculated doesn't leave much room for differences and makes the calculation seem unnecessary. Both of these are very low, as well as being uninteresting in terms of progression. The same goes for the duration.Specifics: The Spirit Caller can unleash a Howl which causes Fear in all enemies. The DC is equal to 10 + 1 per 4 character levels. The Fear effect lasts 1 round + 1 per 4 character levels.
I propose that the DC and/or effect time adds Charisma modifiers or Intimidation in some way (for example in the same way that bard songs use Perform), to make the feat more useful and interesting.