I saw this episode. The ending had on edge and ready to punch someone. But the next episode left me so relieved. Relied and thrilled, and then curious.
To be honest with you, it seems to me that Gideon was unaware of an important detail. When you make a deal with a daemon, sooner or later they're going to take something from you that's actually worth more than whatever you got from them. It might be your soul or it might be your humanity. They could even force you to kill someone. Why else would that page say, "Do not summon at all costs." My guess is that in season two, its all down hill for Evil Gideon.