Hi guys!

This Ra-Freeze-OTK-Mage is the first deck that can really make use of Mogu Cultist and is currently quite competitive in meta these days.

If played well, you will currently be able to reach winrates around 58-60 % (tested with around 50 games at legend). Due to being especially effective against Libram- and Pure-Paladin but also Beast-Druid decks, I think this type of deck deserves quite a bit attention. To my view it is one of the best OTK-decks at the moment and an effective counter to most of the big-buffed-minion style decks out there.

Overview

• The deck is basically an OTK-freeze mage with an infinite reservoir of freeze spells in the late game.
• It has a finishing-combo with Mogu Cultists that are copied by a bunch of 1/1 Tortollan Pilgrims who again and again 'discover' copies of your Potion of Illusions. It needs a little of practise, but when you are able to estimate how to act in certain situations you will win game after game.
• Needless to say, your OTK-combo aims at filling your board with 7 Mogu Cultists which is pretty easily doable if you control the game by permanently freezing the board - especially if your opponent leaves some Mogu Cultists on your side of the board alive from your last turn.
• When you eventually managed to summon Highkeeper Ra you can copy him with your 1/1 Tortollan Pilgrim --> Potion of Illusion combo as well. By this method you will be able to summon up to four copies of Highkeeper Ra dealing up to 80 damage to your opponent in one turn.
• Moreover, this deck has also a pretty good survivability against early threats and mid-range decks. If it is necessary, you can even play it fairly agressive in the first half of the game. With cards like Astromancer Solarian and Doomsayer the deck has pretty good tools to deal with your opponent's early attacks. It has single target freeze with Frozen Shadoweaver, weapon removal with Acidic Swamp Ooze, some mostly helpful shenanigans with Trick Totem and ways to find appropriate tools for special situations with Wand Thief and Vulpera Scoundrel.

The Endgame OTK-Combo: Summoning the Highkeeper ... 2-4 times in one turn

• When you managed to get to 8 mana and you have a Tortollan Pilgrim in your hand (which won't be very difficult), your 'illusion-party' can begin. Now you can start multiplying your Tortollan Pilgrims. Just select Potion of Illusion a few times till you have your hand full of 1/1 Tortollan Pilgrims, but don't forget to choose at least one Frost Nova or Blizzard (and maybe also one Counterspell) every turn.
• Frost Nova is usually the better option here, since it doesn't cause any change on the board (beware of enemy deathrattle minions!) and leaves for your opponent no space to play new battlecry minions.
• When you have a Mogu Cultist you can start copying it as well until you have enought to start your OTK-Combo, but be careful that you not run out of 1/1 Tortollan Pilgrims.
• For that it is important to get rid of other cards in your hand first, so that you don't lack space. On the board, you can use the frozen wall of enemy minions to get rid of your minions that you don't want to copy. 

Explaining some specific card choices and possible replacements

• Having Counterspell in the deck seems to be a little bit inconsistent at first glance, since you have a small chance to miss Potion of Illusion when playing your first Tortollan Pilgrim. However, this won't happen very often. Yet, having the opportunity to have a Counterspell active every turn (while continuously freezing the enemy's board) brings you in the position to be even more safe and totally in control of the late-game.
• However, if this is to risky for you, you can also leave out the Counterspells and replace them by cards that may help in the early or mid game like Lab Partner, Cult Neophyte, Escaped Manasaber or even Spellbook Binder.
• Cards like Novice Engineer, Loot Hoarder and Bloodmage Thalnos give minion-based card draw and tempo.
• If you want to play a more budget friendly version of the deck, you can easily go without Astromancer Solarian and Bloodmage Thalnos replacing them by any cards that bring some early game help - just don't include any other spells.
• The Sphere of Sapience, on the other hand, is quite important since it helps a lot to make the deck more consistent and playable. Just use it to keep at least one Potion of Illusion and one freeze spell in your deck.

To sum up briefly: Playing this deck is a lot of fun - and very sucessful.

Sirius_A