I mean, if you are going to go wild with the Deciever options, there is one that is both obvious and near impossible without the Deciever.
@BoneyM Have a taste of Deceiver use:
"See Moulder is a distant problem. The beasts you sell, less so, but Moulder itself? Now that they have been driven from the Eight Peaks, you are a long way from home, and with no friends. How do you think the other clans would welcome you, with your failure? But...
"Everyone and everything has a price. Even failure, even your life. They question you should really ask yourself is simple: What are you willing to trade? Because here's the thing, I'm not terribly well inclined to Skaven, but for something valuable enough? Getting you out of here and to whatever border of the Empire you want to go is an option, if you make it worth my while. After all, you're just one Skaven, even if a well learned one."
"You know who I am; Eshin-clan. You know I can get you out of here. I will get you out of here, if, you make it worth my while. Hells, Moulder are traders at heart. In beasts usually, but information has value of it's own. Perhaps, with such a friendly opening trade, we might establish a more permanent and lucrative arrangement, for both sides. Repeat customers mean more wealth for everyone, after all. And hells, you might return home with news or treasures good enough to wipe away your failure here. After all, Moulder is but one clan. And even after the traitors are dealt with, there will still be other rivals, no?"
"Of course, for repeat trades first you'd have to prove that some rat won't stab you the moment you return. A deal struck with a dead merchant isn't worth much, is it? "
*********
The most valuable thing you can promise a Skaven, is their own life. A promise that you will help them escape/release them, or even transport them far from the place where all are their enemies, and then free them, is a valuable, valuable thing indeed. Being able to negotiate the price of that release, look him in the eye and tell him you will free him, and have him believe it? That is a powerful hook to use in any interrogation.