Mulligans
This deck gets a ton of cheap spells, reduces the cost of them with Palm Reading, and then can do a variety of things with them. First, you can reduce the cost of Malygos, Gift of Luminance, and Holy Ripple using Nazmani Bloodweaver + cheap spells, Palm Reading, and G’huun the Blood God to have an OTK finish. Secondly, you can play Pen Flinger with those cheap spells to get a lot of burst damage. Thirdly, you can play Yogg-Saron for a chaotic swing turn, potentially ending the game with Rod of Roasting. Fill it in with some of Priest’s classic control tools, and you have a very flexible combo deck!