Does anyone know what was happening outside the bathroom?

There were so many random things that happened outside of the door that are never explained. Like when they're petting the dog and all of a sudden you hear a random voice say, "I am a good boy!" Who the hell said that? Whose tongue did they cut out? The dogs or the guy or something else? Why was it still moving. Why did she eat it?

What kind of spell/ritual did they cast that brought about everything? It was their spell that caused it all, right? They talk about casting a spell on a guy who ended up dying but they don't talk about anything else