This is my first time writing a guide, so any constructive feedback would be helpful for me. Anyways, let's start (also, I'm not sure if this is a midrange deck, so correct me if I'm wrong :P)
This is a druid dragon deck that I've been messing around with for a while, and I actually find this deck to be quite decent. Early game is all about the enchanted ravens, living roots, and druid of the saber. I like to put in 2 Druid of the saber because I love to use them as to how a Warrior would use a Fiery Win Axe. Keeping a stealth 3/2 to pressure the opponent into unfavorable trades will open u up for an easier board control later on into the game.
3-drops: This seem kind of odd, but I found Violet Illusionist to be more useful than I have anticipated. This card pretty much guarantees a free 1 dmg next turn. Now here I'm not sure if I should opt out a Mounted Raptor for another Blackwing Technician due to its bigger body, but either way, turn 3 is pretty standard in terms of minions. just drop them on-curve if possible.
4-drops: not rly much to say here. keep swipe for board clears, or just use on priority targets. There is rly no reason to play Twilight Guardian without dragons in your hand unless it's clear that u are extremely behind. Cult Master should usually be dropped only if you are about to trade in at least 1 of ur minions that is going to die in the process.
5-drops: The most optimal starting hand in most mulligan cases is having an Azure Drake in ur hand. Since AD is a dragon, it will trigger the Blackwing Technician battlecry, and plus it costs 5, so it's easier to play on curve. I cannot stress the importance of Blackwing Corruptor: It should almost always be used b4 Azure Drake. The 3 dmg will kill off most of the 2-drops, and even some 3-drops. At other times, it makes trading more favorable. Having plentiful dragons in this deck, triggering this effect is a piece of cake. Prince Malchezaar is like the back-up of the 5-drop options on turn 5. If, by any means, you have Blackwing Corruptor but no dragons to activate, PM is an ideal choice since 5/6 is quite a decent body.
6-drops: In my honest opinion, Book Wyrm is one of those underrated tech cards in the expansion. This card is basically mixing a 4-drop body and Shadow Word:Pain together. The most obvious argument to why u wouldn't put this in the 6-drop slot would be because by turn 6, no one would be playing minions w/ a 3 attack. The thing here is, u often need to use other cards to get rid of those annoying 2 or 3-drop minions with nasty effects. This card just outright destroys them. Here's an example: Mage's Flamewaker. For most druid players, they would automatically use Swipe or Wrath+Hero power just to get rid of this 1 card. Book Wyrm not only deletes it in one card, but it also establishes a 3/6 body on the board, forcing your opponent to not only have to deal w/ losing a 3-cost minion on their side, but also w/ an additional 3/6 body on your side (This is ofc just an example.) Drakonid Crusher is a great way to cheese your opponents in most cases because most people don't run this card anymore. Putting your opponent below 15 health is easier than you think(unless it's a warrior), and a 9/9 body at turn 6 will put tremendous amount of stress to your opponent as they will be forced to invest more resources in killing it, which in turn, might actually keep your 8-drop and 9-drop relatively safe from hard removals.
7-drop: 5/10 w/ taunt. Do I need to say more?
8-drop: Chrommagus is great for providing additional resources that u need to kill that extra minion, or that extra spell to finish your opponent off. u can combo this card at turn 10 w/ Wrath to get the effect.
9-drop: high health, decent attack dmg, and an effect that pretty much grants you a win if u can let it stay alive on board for more than 2 turns, which isn't hard if you played your previous turns right.
So here it is, end of the guide. Hope u enjoyed it guys :). Again, I appreciate any helpful feedback