Tiberius
Explorer
Horrid Wilting is a great anti-familiar spell. It can affect multiple targets, does a great deal of damage, and grants a Fort rather than a Reflex save, thus bypassing Improved Evasion. Disintegrate is also pretty good, and an area-effect PWK will probably kill one, given their low hit points. Granted, these are all high-level options. For lower levels, I suggest Sleep followed by a CdG. 
-Tiberius

-Tiberius