What is it saying when Imp is spawning?

[SkyL3R]

Is there a way to find out what is it saying when the pentagram on the floor appears and Imp is spawning?
I hear something like "Wastashi nas" but it makes no sense to me.
The phrase should be in Latin, right?
Does somebody knows what is it actually saying and what does it mean?
I am really interested in it.

[Phade]

I'm pretty sure its something in Latin. in which case I definitely cant translate.