Mulligans
You could swap Nightscale Matriarch for a White Lady considering there is no other concepts of healing other than your hero power in this deck. Therefore a White Lady maybe the better option for this deck as (all the dragons in this deck have higher Hp than atk) it will help boost the power of all your dragons (keep in mid though she costs 6 mana and most likely won’t be in your hand during this turn). I was considering Pint size potion and Shadow word: Horro within this deck as a early game combo board clear to help your bad early game pressure. I do value this combo highly as it can help you with any 5 or less atk board (Aggro decks). If you find yourself struggling in the early game i would definetly consider adding 1 of each card in your deck . You might ask why i have added in “Holy water” into this deck, well i value this card alot, yes it costs 5 mana, however the way i see it, if you hold this card for when your opponent plays a strong card this card really comes into play and makes it a very viable card for any priest deck (Plus is does 4 dmg, which isn’t bad).
Lastly, (for this deck i would additional recommend “Prince Malchezaar” as another card, i do like this card in dragon decks as the additional legendaries really help balance your deck out (1 card for an additional 5 legendary minions).
Any feedback would be much appreciated as it would help myself in modifying my decks, don’t be too harsh on myself thanks (Keep in mind this is theory crafted for the rotation).