M4 Death Ventriloquism

You cast a spell that appears to be speak with dead in all forms except you control what the corpse says. Casting this spell prevents any future casting of speak with dead with this corpse. Any living person hearing the spell may attempt a Will saves or use Spell Resistance to disbelieve the spell. Any attempt to determine the false nature of the spell can be detected with a successful mysticism check and a successful perception check. The DC to determine this effect for all checks is equal to 10 + 1/2 your level level + your Wisdom modifier. Any check that fails reads the spell as speak with dead.

Thoughts?