On my journey to finding a faster priest deck, I seem to have hit the jackpot. This is dragon priest, but with a more consistent early game. The goal of the deck is to curve out with overstatted minions, keep board control, and gradually push for face damage. You will find that many games end before turn 10.
I'd also like to note that this is only my second time hitting rank 5, with the last time being 5 seasons ago. I'm actually surprised how easily I was able to rank up with this deck, with a win streak from ranks 11-8 that I just wasn't able to achieve with other decks in past seasons.
In your starting hand, aim for Northshire Cleric, Twilight Whelp, Wyrmrest Agent, Faerie Dragon, Blackwing Technician, and Kabal Talonpriest. Against Shaman, Warrior and Rogue, keep Holy Smite to deal with Small-Time Buccaneer as well as other early game drops. Keep Twilight Guardian if you can curve out well.
If you keep cards that need a dragon to activate their battlecries during the mulligan, make sure to keep a dragon so that you can actually use them. This is a general rule for dragon decks.
*Notice the amount of cards that are good to keep. A good starting hand should come often.
Why is (card) in the deck?
Holy Champion - IMO one of the most underappreciated cards. Allows the deck to push for face damage. This card can be preettty insane when used with Holy Nova, allowing it to gain more than 5 attack sometimes. It's also a good play on turn 6 to drop Holy Champion and heal something else.
Holy Nova - A boardclear that can be played earlier than Dragonfire Potion while still having synergy with Holy Champion and Northshire Cleric. The fact that it heals your own minions too helps to keep minions alive on your board. Against decks that you don't really need board clears for, like Renolock, sometimes it is good to just play Holy Nova just for the mass heal rather than to kill an opponent's minion.
Drakonid Operative - Easily one of the best cards in the new expansion. It's a 5 mana 5/6 with the potential to give you a card that's good for the current situation. Sometimes you'll find Ragnaros the Firelord and have lethal next turn; sometimes you'll pull an Acidic Swamp Ooze and destroy that upgraded 4/2 Fiery War Axe. It's also not a bad play on turn 5 if you don't have a dragon.
Defender of Argus - Against aggro decks, it can save a lot of life. Against control decks, it's good for pushing face damage.
Why isn't (card) in the deck?
Blackwing Corruptor - You'll usually want to already have board control by turn 5, so the battlecry isn't as effective as it seems in this deck. 5 mana for a 5/4 body isn't ideal either.
Dragonfire Potion - It doesn't serve the purpose of the deck as well as Holy Nova can. Many of the minions you play - notably Blackwing Technician, Kabal Talonpriest and Holy Champion - get damaged by this card.
Thanks for looking at my deck. I will answer questions in the comments.