I am going to give basically a brain dump of what I have been seeing with Izzet. It seems to be close to good, but not quite there yet. Perhaps you can find the missing link to push it over the edge.
Here is the list I have been testing with. I am pretty sure that Merchant Scroll should have been a Mystical Tutor instead.
Land Base
2 Polluted Delta
3 Flooded Strand
4 Volcanic Island
2 Underground Sea
3 Island
1 Tolarian Academy
Acceleration:
1 Black Lotus
1 Lotus Petal
1 Mox Ruby
1 Mox Jet
1 Mox Sapphire
1 Mox Emerald
1 Mox Pearl
1 Mana Vault
1 Sol Ring
1 Mana Crypt
Broken Draw Engine:
4 Izzet Guildmage
4 Manamorphose
Alternate Win:
1 Empty the Warrens
Broken black Cards:
1 Yawgmoth's Will
1 Demonic Tutor
Control:
4 Force of Will
4 Mana Drain
Draw Engine:
4 Cunning Wish (Ancestral in board)
3 Intuition
4 Accumulated Knowledge
Broken Blue Cards:
1 Merchant Scroll (Should have been Mystical Tutor)
1 Time Walk
1 Ponder
1 Fact or Fiction
1 Brainstorm
Dredge Sideboard:
3 Pithing Needle
4 Leyline of the Void
Wishboard:
1 Ancestral Recall (Draw)
1 Vampiric Tutor (Tutor)
1 Reset (Combo)
1 Lava Dart (Welder, also Primary win condition)
1 Pyroblast
1 Red Elemental Blast (Could also be Vexing Shusher)
1 Rebuild (Stax)
1 Echoing Truth
The primary win condition is to Cunning Wish for Reset and then use Reset and Izzet to generate infinite mana. Then cast a draw spell like Brainstorm or Manamorphose and draw your whole deck till you find another Cunning Wish. Finally Wish for Lava Dart and keep copying it till your opponent's life total is 0.
Why use a Cunning Wish engine? Ancestral Recall is busted, but after that various random control and win cards like Reset, Fire/Ice and Echoing Truth can sit dead in your hand. I figured I would pull out the utility and just run 4 Cunning Wish. The first finds Ancestral and then by the time I go to Wish a second time I am ready to win. Cunning Wish has several advantages. First it is 100% instant speed. This is convenient in a deck that wants everything to be instant speed. Second it is more flexible in that it can find more answers than Scroll could. Finding Pyroblast or Lava Dart is very convenient. Cunning Wish's main disadvantage is barely that. It costs 1 more which means you cast it with 3 mana up. This means you have 4 mana up on the turn you cast Ancestral Recall which means you can copy it with Izzet out. The problem I ran into with Intuition/AK is that I would Intuition using 3 mana on turn 2 and then I would find myself on turn 3 with 4 mana. This was 1 shy of what I needed to copy AK. Cunning Wish->Ancestral Recall really smooths things out.
Manamorphose is just busted in this deck. You can use it to cast turn 1 Izzet. You can also use it to cast a turn 1 Mana Drain. Manamorphose is most broken as a Drain sink with Izzet out. If you drain into say 7 mana then you can play Manamorphose and 3 copies to draw 4 cards and still have
floating. This means that if you draw Empty the Warrens or Yawgmoth's wIll you are really in business. You can even use the mana to cast Ponder and copy it.
Manamorphose is really good for making your Yawgmoth's Will powerful. It simultaneously fixes your mana and draws cards for free.
Finally when you combo out with Reset you need either a second Cunning WIsh in hand or you need a draw spell. Manamorphose acts as that draw spell quite frequently.
By the way, you should basically never sit on Manamorphose. You should use it as soon as you are going to pay mana for something. You will draw into other Manamorphoses later.
Why no Thirst?
There are two directions to go in regards to a backup win. One option is Tinker->DSC. The other is Empty the Warrens. Once I added Manamorphose to this deck I found that I was generating a lot of storm. For this reason I chose Empty the Warrens. Paul Mastriano just showed how good Tinker->DSC at worlds so that might have been wrong. If I were to run Tinker->DSC then Thirst would be better and I would be more inclined to run that. As long as Warrens is the backup win then Thirst is just not as good as other options like Ponder, Manamorphose and Cunning Wish.
The second strike against Thirst is that it cannot be copied. Manamorphose, Ancestral and AK can all be copied. Intuition and Cunning Wish find AK and Ancestral respectively so those find cards to copy. In all liklihood thirst will find a card to copy, but it cannot be copied itself and it is not as busted as Fact or Fiction. I would probably add a copy of Gifts Ungiven before I added Thirst.
Thirst is really good with the Intuition/AK engine so it would be nice to find room. It is a good card. I just cannot find the room.
Why 4 Izzets? First of all Izzet is really good in this deck and it makes the deck go. Izzet is frequently countered or removed so having a second is nice. Also, with Manamorphose in the deck, turn 1 Izzet becomes far more likely. This means you want to see Izzet in your opening hand rather than just trying to find it by turn 4 when you can play it with Drain backup. Finally Izzet can be pitched to Force and it beats for 2 so it is never dead.
Testing results have been mixed but generally Xerox has been too slow. I actually did okay playing against Long because the turn 1 Drains were pretty good. I did notice that having a Mana Leak in the board to Wish for could be helpful.
I defeated Parfait 5-1 with Xerox which means little since Parfait is miles and miles from being a tier 1 deck.
I then lost to the Drain Tendrils/Slaver/Painter hybrid that I posted on TMD 6 weeks ago. The record there was 1-5. I was running Commandeers in Painter's board and those are amazing in the AK mirror so that was a large part of the loss. Also Welder and especially Sundering Titan are vary painful for Izzet.
Finally Xerox tied Deez Goyfs 3-3. This is actually a good sign since Deez Goyfs has been testing fairly well against most everything else.
I have also tested this list at a ton of magic nights, but many of the decks are not tier one. Generally mana denial is not that problematic, with Sundering Titan being the exception. Sphere of Resistance is not that bad because it does not increase the cost of copies. For instance you can still play Ancestral and copy it for a total of 5 mana. Paying 5 to draw 6 cards is busted. Also, the mana curve is really low. Including Drains and Manamorphose there are 33 mana sources and the vast majority of spells cost 2 mana or less. The exceptions are Warrens, Yawg, Fact, 3 Intuition and 4 Cunning Wish. That is only 10 cards that cost more than 2 and of those only 2 cost 4!
Turn 1/2 combo is not that bad because Manamorphose get Drain on line on turn 1 so often. For this reason Belcher is not that scary.
Slow control decks are easily out drawn and defeated.
Fish is not that much of a problem because Izzets can block annoying creatures and Cunning Wish provides various outs.
The biggest problems are turn 3 combo decks. These decks basically expect you to have Drain up before they win. They are prepared to play a flury of must counters by turn 3 or they expect to have Force of Duress backup. Unfortunately Long is morphing in this direction since Long decks are now a bit slower but running 4 Force and 4 Duress. The Painter deck that crushed Izzet generally goldfishes by turn 3 so that was part of the reason it was so problematic.
WGDX fits into this category since it wins around turn 3 with Force/Duress backup. Thirst for knowledge might be the solution to bridge that gap. Perhaps even adding Commandeer/Daze/Mana Leak to the board would improve things. I am not sure.
Dredge falls into the turn 3 combo deck. Basically the boarding strategy is to board out Forces and Drain and board in Leylines, Needles and Echoing Truth. The trouble is that your 8 disruption can slow Ichorid down but not long enough to get the draw engine going and draw your win or more disruption.
I have not tested against Slaver yet, but I expect it to be favorable since Izzet used to do great against Slaver. This is pure speculation though.
Good luck!
