The deck hinges on that insane card Goblin Welder. The idea is to get out a 0 cost artifact along with the welder and a Wurmcoil Engine in the graveyard as quickly as possible so you can perform the switch. The deck can fairly consistently get a turn 2 Wurmcoil Engine or sundering tian, which is pretty hard to win a game against as far as I can tell. It started as Izzet, but this mono-red version is faster and more consistent (if more fragile). I have tested this version against some of the best decks in the format (miracles, stoneblade, delver, BUG, MUD, maverick) and it performs surprisingly well and is a blast to play, but it can always be improved. Here's some explanation for the card choices.
Mainboard:
Key pieces:
Goblin Welder - this card is absolutely insane. The rest of the core pieces all need this to work the way they do, so I will describe the interactions in their individual segments.
Wurmcoil Engine - this is the deck's win condition. I chose it because... well, it is huge and absurd. It is totally OK with being in the graveyard unlike the colossus(es) and is virtually impossible to kill with a welder out, as once it dies you can just sac one of the baby wurms it made to bring it back.
Sundering Titan - really big, and usually slows the opponent down pretty well, which is crucial
Myr Battlesphere - hilarious card, also I needed another wurmcoil-esque ccreature (i.e. leaves behind artifacts to sac and reanimate himself)
0 cost artifacts:
Darksteel Relic - I chose this one because it is resilient. I'm not sure that it is the best choice, but it can help protect the combo. Say for instance that my opponent somehow realizes what is happening and can only stop the combo by destroying the artifact... well they can't. That's why I didn't use Ornithopter or something
Lotus Petal - this one is nice because it can provide some mana ramp and throws itself in the graveyard when it is done. This can cause some pretty silly mana ramping if Goblin Welder gets involved, allowing you to recur it multiple times.
Great Furnace - I know this is a land, but it still works pretty great with the welder. If you can somehow get one into your graveyard with another one out on the battlefield, it gives your welders tap: add R to your mana pool (if you would ever need that)
Dig:
Burning Inquiry - digs deep for one mana, and can also screw with your opponent.
Faithless Looting - a good way to dig through the deck, finding pieces you need and discarding engines all the while.
Gamble - searches for whatever you need (though it is risky) and is a sure way to get the big dude into the graveyard with an empty hand. This used to be Gitaxian Probe, and though the probe was pretty good, the fact that it didn't dig very far hurt and the life loss actually matters in some matchups. Gamble performs better for the most part.
Dangerous Wager - thematically goes well with Gamble, also is good for discarding a hand full of wincons and no welders. It's important because it's the only one of the discard spells that always lets you keep what you drew, the best one to use when you need a 0 cost artifact or a Goblin Welder
Goblin Lore - digs the farthest, also lets you keep a card after you cast it, though you cannot chose so it's risky if you need something.
Ramp:
Simian Spirit Guide - quick mana, allows for potential landless hands.
Rite of Flame - more acceleration. Lets me cast multiple Faithless Lootings or flashbacks.
Other:
Lightning Bolt - ever-present, really only for removal if I absolutely need to kill something. may replace with Fireblast
Sideboard:
Blood Moon - if I need to slow down mud or something
Defense Grid - anti-counterspells and removal for control matchups
Ensnaring Bridge - for anything that attacks, really, I rarely have more than one or two cards in my hand after the first turn, but most importantly for emrakul or similar gigantic things
Forked Bolt - just in case I need to kill multiple small things (ie delver, Young Pyromancer, what have you)
Pyroblast, Red Elemental Blast - for control matchups. finding the spare mana to counter a Force of Will shouldn't be too hard. The arbitrary split is just in case someone plays Surgical Extraction or something
Smelt - for artifacts that need to die right away, as in the instant they start existing. I feel like this deck can race most aggressive artifact decks effectively, so I picked instant artifact removal rather than more powerful options (Shattering Spree, etc.) to fight the controlling artifact decks better.
So that's the deck (apart from Mountains, which I don't think I need to explain). Mostly, I need help with making sure it does well against other combo decks, since it isn't an instant-win combo like show and tell, storm, and elves. Ensnaring Bridge goes a long way against elves and emrakul show and tell variants, but it's not perfect. Enjoy, and thanks in advance for the help, it is much appreciated!
Here's the izzet version. It's much less consistent and a little slower, but a little more powerful and resilient. Also it costs like twice as much.
http://tappedout.net/mtg-decks/izzet-a-goblin-welder/
