Ardat, that's the name. Yeah, I thought she was a promising villain but then they killed her off in two seconds flat. So what was the point of her at all? I assume they thought they needed someone to force a reveal of Belphagor's dastardly plan but like you say, he did his own reveal anyway so that made the whole Ardat storyline utterly pointless. it would actually have been more fitting for Ketch to have been killed by Dean last week - this death felt shoehorned in to give DHJ a bit of a nice heroic(ish) send off.