DISCLAIMER: I am not responsible for Loathebs (don't use your Time Warp after he is dropped as the +5 mana cost effect WILL last throughout your extra turn), Dirty Rats pulling Antonidas or Apprentices, Eater of Secrets, Flare, Eye for an Eye or fatigue damage at 1 health, etc.
You can actually recover from most of the above things if you plan ahead, except for Eater of Secrets/Flare and Eye for an Eye if you're at one health. Fatigue should be avoidable and Loatheb will only beat you if your opponent knows the precise turn to drop it (they usually drop him too early).
After some testing, I cannot say I found Echo of Medivh to be superior to Molten Reflection. It does open an extra card slot and allow you to either use another copy for other important minions or an extra Freeze/Doomsayer, etc; HOWEVER, you can't really use it to trigger Tony and it also makes it much, much harder to one-turn combo because you still must play the additional Sorcerer's Apprentices with mana (whereas they become free with Molten).
Ultimately, Echo is such a versatile card in this deck that one copy definitely works its magic. Take a look at the change-log for specific card swaps. Thanks for the support. -Kiz
UPDATE: +1 Mana Wyrm, + Echo of Medivh / -1 Mad Scientist, -1 Ice Barrier
STATS FOR PAST TWO SEASONS (reached rank 5 last season from rank 15 and currently rank 10 this season)
68-32 OVERALL (breakdown of matchups are below)
HOW TO PLAY THIS DECK
-It's a tricky deck, but the goal is contest the board early with your mix of 1- and 2-drop minions, Frostbolts, and Primordial Glyphs. You will inevitably have to give up the board and then simply wait as long as you can before using your freeze spells to stall out the game while you continue drawing through your deck.
-Use your glyphs after your opponent has dropped a minion or two so that you can best pick how to react.
-Frostbolt can be used early to clear threats or late to freeze up a big minion in order to stay out of lethal range.
-How do you beat other mages with Ice Block? Easier said than done, but you want to get your entire combo in your hand before dropping Emperor Thaurissan. While E.T. is not technically necessary in this deck, being able to pull off your infinite Fireball combo, pop the block, and cast Time Warp all in one turn makes this deck that much more potent.
-Calculating your combo can be tricky. If your only chance to win is to pull off a one-turn combo because you haven't completed your quest, then Emperor Thaurissan needs to get a tick on 4 out of 5 pieces (2 Apprentices, 2 Moltens, Antonidas). Just make sure you have a spell ready to begin your infinite Fireballs (if you've discounted the right pieces sometimes the last Molten can be used to begin your chain)
If you've completed the quest when you drop E.T., that's when you'll be able to pop block and cast Time Warp in the same turn vs. Mages or Priests who've stolen an Ice Block.
-Use Echo of Medivh to copy: Doomsayer for extra board clear, Arcanologist to thin your deck, Coldlight Oracle to draw more, Clockwork Gnome for more Spare Parts to use towards the Quest, etc. This is included NOT as a part of the combo, but with the right discounted combo pieces from Emperor, Echo could also be used as part of your TTK combo.
OVERDRAWING & FATIGUE DAMAGE
-Planning out the order you drop stuff will help you avoid overdrawing. Experience with the deck will help you avoid fatigue. Unless you're facing a Mill rogue it's not usually an issue to overdraw.
PLEASE be careful and remember that Time Warp is a spell that will be added to your hand. Make sure you're not holding too many cards with a Clockwork Gnome on board. Make sure you don't have an obscure secret up like Duplicate or Mana Bind which can both be awesome but dangerous while holding 9 cards.
WHY CLOCKWORK GNOME?
I have found that Clockwork Gnome is pretty much the MVP of this deck. The Spare Parts synergize excellently with:
Doomsayer - you can receive Stealth (Finicky Cloakfield) and assure yourself of a board clear or Taunt (Rusty Horn) and one-attack (Whirling Blades) spare parts which both make a huge difference against aggro.
Arcanologist - same as Coldlight Oracle; thinning your deck is hugely important.
Emperor Thaurissan - Stealth him and gain an extra tick on everything. GG.
Sorcerer's Apprentice - you can't put these on the board until your TTK unless.... you have a Time Rewinder. If you have a logjam of spells in your hand, play your apprentice before casting your spells, then your spare part to bring it back to your hand.
Reversing Switch - great for facilitating board trades, removing shaman totems, or just making an aggressive enemy minion less of a threat.
Emergency Coolant - Mixed with your Frostbolts and Cabalist/Glyph freeze spells, you can often muck up your opponent's plan for lethal and delay them while trying to find your Frost Novas or Blizzard or last Ice Block etc.
Did I mention these satisfy the Quest requirements also and for always a guaranteed 1-mana? Spare Parts are the secret ingredient to open the Wild Waygate!
MULLIGANS & CARD CHOICES
Always keep Open the Waygate - duh. Even against PW and Egg Druid. HOWEVER, you should always avoid tipping your hand and never play this on turn 1 if possible. The best turn one play is always....
Mana Wyrm - Excellent for contesting the early board. Excellent for disguising your deck's true intentions. Excellent to draw late! Why? Well, sometimes you're not going to draw your combo in time before your opponent overwhelms you, so Mana Wyrm can instead be used to reach lethal in case Antonidas never made it to your hand or you just couldn't play him. It's not uncommon to get an extra 10-damage out of it at the end. Why not use 2? Good question, but there's only so much room in the deck.
Clockwork Gnome - MVP! MVP! Play this on turn 1 and make your opponent think your a Mech Mage. Save your awesome Spare Parts (like freeze, bounce and stealth) until just the right time for the best results. Ping it vs. Priest unless it's a turn one drop, but don't leave it on the board long vs. those thieving tricksy Priests!
Arcanologist - This is the runner-up for MVP. It's more powerful than Mad Scientist (in this build) because you thin your deck immediately and you're not susceptible to a silence or Priest using Potion of Madness. That said, always keep...
Mad Scientist - With 4 secrets in the deck, if you can thin your deck three times you have a great chance at winning. I cannot emphasize how crucial thinning your deck is. It's more important than using extra card draw like Loot Hoarder or Novice Engineer.
Primordial Glyph - You may keep this if you have a few other one-drops already, otherwise it's often best to toss this away. Personal preference.
POSSIBLE "TECH" CARDS
Yogg-Saron, Hope's End - oh how I love this card. And while Yogg can sometimes be used with spectacular results, it's often hard to find a time to play him in this build. Trust me, I tried. If you want more fun, auto-include. If you want a more consistent deck, don't include him.
The problem with Yogg is that he will often draw you cards and you're almost always going to be holding 7+ if there's an appropriate time to play him. Overdraw your combo pieces and GG. The best timing for Yogg is after you've exhausted your last freeze spell. Yogg is great at flipping the board state and delaying lethal, but if you need to cast Ice Block instead.... well, he just sits in your hand sometimes.
If you're set on Yogg, I suggest you sub out Mana Wyrm and use Volcanic Potion.
Extra Doomsayer - If you want two, I don't blame you. Though I caution sometimes he's just useless or even a liability (against Dr. Boom Boom Bots for example). I would never drop him with 1-health vs. a board that isn't full just in case Dr. Boom is lurking (destroying the bots and taking the damage to your face on your turn does not activate Ice Block, in case you were wondering).
Extra Mana Wyrm - I tried two with no Doomsayers and no Wyrms with two Doomsayers, but ultimately I think one here is the right call. There's just other higher priority cards that can't be cut to add another.
Volcanic Potion - Great vs. aggro, but that's kinda what your early minions are for. Inconsistent because sometimes you have the board early. It's best to get one of these from a Glyph.
Babbling Book - I advise against this. This deck thrives because of the Spare Parts and with those, Glyphs and Cabalist's Tome, it becomes unnecessary and a weak body which won't really help contest the early board.
Spellslinger - This was a pleasant surprise, but ultimately I just don't think there's room for him. The body is good and it's a great turn 3 play when you already have a few minions on board, but ultimately not necessary to complete the Quest.
Blizzard - Why not 2? Boom Bots can make it a liability. No room. Also, you can discover freezes from Glyphs or Tome.
Bloodmage Thalnos - Possibly my favorite legendary for it's versatility. It probably couldn't hurt to him somewhere, but finding a card to cut for him is hard. He serves as more of a luxury (like Yogg) in this deck.
MATCHUPS & HOW I FARED
PALADIN (13-5) - My most common opponent was Paladin and there were a wide variety. As best as I could tell, these were the decks I faced:
Token-Divine (4-3) / Murloc-Aggro (3-0) / Buffadin (3-1) / Control-Taunt 2-0 / Secret 1-1
PRIEST (8-4) - Control (2-0) / Quest (2-2) / Lyra (2-0) / Dragon (1-1) / C'thun (1-0) / Reno (0-1)
WARLOCK (11-1) - Reno (7-0) - avoid a bad Dirty Rat and you win, beware of Deathlord as well / Zoo (3-1) / Discard (1-0)
WARRIOR (8-4) - Pirate Warrior (3-4) - probably statistically a worse matchup than this. Ship's Cannon can wreck havoc / C'thun and/or Quest Control (5-0) - Same as with Warlock, avoid a bad Dirty Rat and you should win this matchup.
MAGE (5-7) - Aggro-Secret Mage (1-4) - This is a nasty matchup / Freeze (3-2) / Reno (1-1)
SHAMAN (8-3) - Jade (2-2) / Quest (2-1) / Elemental (1-0) / Aggro (1-0) / Kel'thuzad Ancestral Spirit sillyness (2-0)
DRUID (6-4) - Aggro-Egg-Token Druid (2-3) / Jade (2-0) / Beast Druid (1-1) / Ramp (1-0)
ROGUE (7-0) - Mill (4-0) - I feel like this was very lucky. When I was milled, combo pieces were missed or I already had them. Sometimes the extra draw ends up working out / Miracle (2-0) / Jade Raptor (1-0)
HUNTER (2-4) - Bad matchup. All were that aggressive mid-rangy deck you see out there since Hunter doesn't have much else.