Deck Overview

We'll just quote Ike's own words: "Water Elemental on 4 = Shaman conceding". Shaman struggles against faster and more aggressive decks and stalling tools. Well, Mage has both: on one hand, Jaina has lots of burst and Spell Damage synergy; on the other hand, Ras Frostwhisper and Frostbolt can easily buy you a turn or two, which are vital if you want to win.

Being able to consistently deliver a Water Elemental attack to the opponent's face prevents Boggspine Knuckles swings and therefore all the snowballing it provides. Moreover, when you're done stalling and buying time, you can use the Mana Giant-Conjurer's Calling package to close the game in your favor.

The Card Draw Engine

Elemental Mage's backbone is definitely its draw engine. Having your hand always full means that you can pull off Mana Cyclone turns consistently and get faster to the cards you need in order to counter your opponent at the same time.

Cram Session is more reliable than Elemental Allies since it immediately draws a card and therefore doesn't need much set up. Moreover, it is one of the best turn 2 play to follow up an opening Lab Partner.

On the other hand, Elemental Allies guarantees more (and specific) draw with the upside of setting up future Mana Cyclone turns. The deck runs many Elementals (which we'll talk about in a minute), but you'll usually end up completing this Sidequest with Confection Cyclone, a card that seems to be printed specifically to push Elemental Allies into the meta.

Stalling Tools

Shaman's degeneracy mainly revolves (pun intended) around two cards: Revolve and Boggspine Knuckles. While you can't do much against the former outside of value trading and filling your board with minions, there's a simple counter to the weapon - if your opponent is frozen, they can't swing. To be honest, your main goal is keeping your Shaman opponents fresh between turn 4 to 6, when the Evolve mechanic really breaks the game, but the more the merrier.

Frostbolt is the quickest and cheapest way to Freeze your opponent's face, but Water Elemental guarantees multiple stalling turns and a must-kill target at the cost of being way slower.

Planning for your future turns is important: if you have Ras Frostwhisper and Lab Partner in hand on turn 4, consider holding your Primordial Studies discount effect for another turn in order to get a 5 mana 4/9 that deals 2 damage to every enemy and can even scale if not dealt with. Moreover, Ras lines up extremely well against Desert Hare and (if you have Spell Damage) Pit Master.

Elementals and Cyclone Package

Violet Spellwing is a decent turn 1 play that grants a progression towards Elemental Allies' reward and a cheap spell for Mana Cyclone or just some simple damage - not the best card in the deck, but having early game helps and the synergy is right there; Not playing it would be foolish.

Confection Cyclone's Sugar Elementals work towards both Elemental Allies's completion and Mana Giant's cost reduction. That's right: unlike its brother Arcane Giant, this giant gets a discount from every card that didn't start in your deck, not just spells. Being a Fire Fly on steroids, Confection Cyclone is a card we expected to see played at some point, and here's its first occasion.

Mana Cyclone is too famous to need any presentation. Together with [Hearthstone Card (Sorcerer Apprentice) Not Found] and a bunch of cheap spells (great with Ray of Frost and Magic Trick) it can grant remarkable hand refill. Sure, Elemental Evocation is not legal anymore, but the card is far from being unplayable.

Mana Giant is the top-end of this deck - while you want to drop it for the least amount of mana as possible and then Conj it, you can also play it as an 8/8 that counts as an 8-drop towards a Revolve - quite difficult for your Shaman opponents to deal with since most of their minions are small before the Evolve proc.

Mulligan Tips and Tech Choices

• Lab Partner is always a must keep: 1 mana 1/3s are sticky and, as mentioned before, you can follow it up with Cram Session, but double Ray of Frost is acceptable too if you think you'll need to get rid of a dangerous minion like Phase Stalker.
• Elemental Allies is another keep depending on the rest of your hand: if you have Confection Cyclone, you can hit the dream curve pretty easily and draw 3 spells that will help you later on only on turn 3.
• If you're on the coin, you can consider keeping Mana Cyclone and Wand Thief, but most of the time you should take this decision based on the rest of your hand as well. 
• Magic Trick, Primordial Studies and Violet Spellwing are all decent keeps for the turn 1 play, but if you already have Lab Partner or Elemental Allies (see above) we'd advise to toss and look for something else.
• If you're tired of getting repeatedly Edwin-ed on turn 3 4, then you should tech in a copy of Devolving Missiles just to smoothen up the match-up against Rogue - not that necessary now that Rogue has been hit, but if you really want to piss off people go ahead.