When the Krark-Clan Ironworks deck first appeared online several months ago, I was so intrigued by the deck that I immediately threw a copy together and started goldfishing it to get a feel for the mechanics of the combo.
It was so fun I couldn't stop. I goldfished the deck for hours. I think I finally forced myself away from my computer around three in the morning to get some sleep, but I wasn't happy about it. The combo turn plays out a lot like Elves in Legacy, where each artifact you cast ends up both netting mana and cards, turning your deck into a perpetual motion machine of awesomeness.
In this house, we don't obey the laws of thermodynamics.
On top of being fun, the deck has serious legs as a Turn 4 combo deck with a ton of built-in resilience to disruption due to the heavy number of cantrip effects. There are, however, a few issues that have kept the deck from ascending to the upper echelons of the format.
First, Stony Silence is, to put it mildly, problematic. Your best answer to permanents is Engineered Explosives, so you have to have another answer almost entirely for this card. Abrupt Decay does the job admirably, but having two outs to a popular sideboard card that otherwise kolds your deck is less than ideal.
Second, the deck is entirely dependent on finding Krark-Clan Ironworks, which adds a lot of inconsistency even with high velocity. This list seeks to remedy this issue by incorporating Whir of Invention, which is expensive, but easy to improvise down in this deck. Getting four more copies of your key card, and Scrap Trawler for that matter, is a key upgrade.
In order to support improvise, the win condition has shifted to...Shriekhorn? Yep. With a Scrap Trawler and KCI on the battlefield, you can loop two Myr Retrievers returning each other while the Scrap Trawler gets back Shriekhorn, milling them for two during each loop. Of course, if milling won't work, you can loop Pyrite Spellbomb, although you'll also need a Mox Opal to return when you sacrifice the Spellbomb. This gives the deck access to a few more cheap artifacts, as well as Myr Retriever, which can buy back combo pieces while you chump block an attacker.
I don't know how much better these innovations make the deck, but it's still among the most fun decks I've ever played, and that has to count for something.