Hearthpwn

(Dec 22, 2018) Deck Update - Meta Nerf
I replaced some cards for the new meta and updated the match-up guide.

(Dec 10, 2018) Deck Update - Rastakhan Meta Stable
The mata is becoming stable. I further replaced some cards for the change of meta.

(Dec 07, 2018) Deck Update - Rastakhan Launch
Introduction of Rastakhan has given this deck more flexibility. I replaced some cards.  

Do not forget to upvote this deck if you find this guide useful. Your kind support is my energy to try out new decks and write detailed guides. 

(Dec 09, 2018) - Rastakhan Meta Stable

I replaced a Doomsayer with Zola the Gorgon as we have quite a lot of situational Battlecry cards. It could be play on the minions depending on the tempo and opponent's type to get an extra copy. (When you would like to get an extra copy of Ragnaros the Firelord, remember to play Zola the Gorgon on Jan'alai, the Dragonhawk if it is available.) The Match-Up Guide is also written.

(Dec 07, 2018) - Rastakhan Update

The meta is still very volatile with the introduction of different decks. Some notable decks are Spell Hunter, Odd Paladin (...again), Freeze Shaman and Dragon Warrior.

I replaced Acolyte of Pain with Pyromaniac as it is of better value and potential to draw more cards. Jan'alai, the Dragonhawk, as expected, is introduced because Ragnaros the Firelord has recently become an Elemental, which would have insane synergy with Frost Lich Jaina. As to fulfil the condition of Jan'alai, the Dragonhawk, I further proposed to substitute The Lich King and one Voodoo Doll with two Spirit of the Dragonhawk, which is also quite useful to play against aggro decks in the early game, draw more cards with Pyromaniac and summon multiple Water Elemental (Yes, it does!!) when Frost Lich Jaina is in play.

These substitutions make the deck even more stronger than it was. I have been reading complains about the difficulties to play against aggro decks, and sometimes you might have nothing to play from your hand - these have been all solved! With the aid of Spirit of the Dragonhawk and Pyromaniac, you can now control the board against aggro opponents. The average mana cost is also reduced which means you can play more cards in early turns. In the past, if you have noting to play, you may just ping your opponent, but now you can stake your damage to fulfil the battlecry condition of Jan'alai, the Dragonhawk. 

I have been having very high win rate with this deck, from R4 to Legend this season. The idea of this deck is to control the board by your early clears and hard removals to survive until late game. Once you play the key cards in the late game, you will beat your opponent in or near fatigue stage. This deck is superior in most of the match-ups as there are counters towards those top-tier decks. The cards are concisely categorized into the following functions.

Board Clear

• Doomsayer - Play early to keep safe until you can play the following spells.
• (*) Daring Fire-Eater - To kill minions in the early game or stack for Ragnaros the Firelord. You can also summon Water Elemental when Frost Lich Jaina is in play. 
• Dragon's Fury - Remember to use before your other spells are drawn.
• Blizzard -  Play if you have no other options, or followed by other removals next turn.
• Flamestrike - Deal 4 damages to all enemy minions.
• Baron Geddon - If you play after Frost Lich Jaina is in play. It could heavily heal your hero.

Hard Removal

• Voodoo Doll - Play when Frost Lich Jaina is in play to give you a Water Elemental.
• Polymorph -  Frost Lich Jaina is in play to give you a Water Elemental and rule out the chance that your opponent resurrects it.

When you have both, you are advised to play Polymorph because Voodoo Doll can be played with less mana and on elusive minions. However, Polymorph can bypass the Deathrattle effect of minions.

Deck Filter

• Raven Familiar - To draw a spell in the early game. You can replace this card with Doomsayer and Voodoo Doll.
• (*) Pyromaniac - Card-drawing tool with 3/3/4 value (much better than 3/1/3). Value of this card can be magnified by Spirit of the Dragonhawk.

Anti-Deck

• Gluttonous Ooze - It is a very strong card to play against Druid, Rogue and Warrior. See Match-Up section below to know more about how to play this card.
• (*) Zola the Gorgon - You can play this card for an extra copy of your minion on the board, depending on the situation. You can always copy a Doomsayer or Stonehill Defender to survive against aggro decks. When you would like to get an extra copy of Ragnaros the Firelord, remember to play Zola the Gorgon on Jan'alai, the Dragonhawk if it is available.
• Stonehill Defender - Save your life in the early game. It could also be very useful if you discover some overpowered cards like The Lich King in the late game. 
• (*) Arcane Keysmith - It is a very strong card to play against a lot of meta decks. See Match-Up section below to know more about how to play this card. Splitting Image is discoverable in Rastakhan. 

Key Card

• Arcane Artificer - Armor up your hero into late game. 
  
• (*) Jan'alai, the Dragonhawk - You can stake your damage by pinging your opponent in the early game. With Spirit of the Dragonhawk or Daring Fire-Eater, you can stake faster. Please note that Ragnaros the Firelord is an elemental.
• Dragoncaller Alanna - Provide stressful board for your enemy in the late game, especially during fatigue stage.
  
• Frost Lich Jaina - This deck would be meaningless without this card.

Match-Up (Last Updated: Dec 22, 2018)
If you play this deck for a long time, you will find that there are counters towards each top-tier deck.

• Malygos / Togwaggle / Taunt Druid
  You can always use your Gluttonous Ooze for Twig of the World Tree to prolong your opponents' time for their combo. You are advised to put early board pressure to your opponent.
  (1) For Malygos Druid, you can use your Arcane Keysmith to discover Explosive Runes for Flobbidinous Floop, and Counterspell for Malygos.
  (2) For Togwaggle Druid, you can use your Arcane Keysmith to discover Frozen Clone, Counterspell and Mana Bind for King Togwaggle.
  (3) For Taunt Druid, Polymorph and Counterspell can dilute your opponent's chance to resurrect a Hadronox by Witching Hour. Polymorphing the big taunt minions can also prevent them being summoned by Hadronox Of course, you can store your board clears in case they are lucky enough to resurrect the Hadronox.
  
  
• Deathrattle Hunter
  Simply control the board and Polymorph the Deathrattle cards of your opponent.
  
  
• Spell Hunter
  Utilize your Dragon's Fury for the Spellstone. You will usually have to survive the early game and defend your opponent until they were killed by fatigue. However, you could replace some removals with card like Astromancer, Pyros, Pyroblast or any early minions that could control the board. 
  
  
• Zoo / Discard / Even Warlock
  (1) For Zoolock and Discard Warlock, mulligan for the early drops.
  (2) For Even Warlock, do not overdraw your deck. Keep a buffer of three more cards than your opponent to survive in the fatigue stage.
  
  
• Mecha'thun Decks
  Do draw your deck quickly to find the card you need as follow.
  (1) For Priest, you will notice that they will draw up their deck and start their OTK combo when they have 5 cards left in their hand. When your opponent has 5 cards in hand and no card in their deck, play Arcane Keysmith to discover Explosive Runes for Reckless Experimenter.
  (2) For Warlock, play Arcane Keysmith to discover Counterspell for Bloodbloom when their deck is empty and both Galvanizer are played.
  (3) For Warrior, play Arcane Keysmith to discover Counterspell when their deck is empty.
  
  
• Resurrect Priest
  Simply Polymorph Malygos and Prophet Velen and play Arcane Keysmith to discover Counterspell when you feel that your opponent's combo is ready.
  
  
• Control Mage
  Do not overdraw and be cautioned of the cards your opponent has not played.
  
  
• Other Aggro and Mid-Range Decks
  Survive in the early game by board removals and mid game by hard removals. If you reach late game, the game will be yours. Arcane Artificer would be a good companion. You can also consider replace a Voodoo Doll with Doomsayer. When you play Stonehill Defender, remember to discover the minions that are the most essential in the situation but not the strongest.