Sonic damage! Is there nothing that can stop it? Even the Destrachen can't!
Protection from Sonics (Ex): While they can be affected by loud noises and sonic spells (such as ghost sound or silence), destrachans are less vulnerable to sound-based attacks (+4 circumstance bonus on all saves) because they can protect their ears. A destrachan whose sense of hearing is impaired is effectively blind, treating all targets as totally concealed
On the other hand, you don't see too many spells with the [sonic] descriptor now do we? (of course, there's always the metamagic feats energy admixture and energy susbstitution)
You can never hope to grasp the source of our power. We are forever.