what is zangetsu saying when he uses form is emptiness?

I wonder what zangetsu says when he perfoms the form is emptiness attack, it sounds like kerusaku seseki but that isn't a term in japanese, what i do know is that it's problably based of omnia vanitas, which is a move julius belmont could perform in aria of sorrow and harmony of despair (btw, omnia vanitas is a latin phrase that translates to all is vanity), but it doesn't sound likeany latin i've learned or heard, any ideas what it is?