Arcum Dagsson, on the outside, doesn’t look all that impressive. Before I begun the research for Arcum, I thought he was a mediocre general, but then I took a good look at him.
2UU for a 2/2 Legendary Human Artificer that has a tap ability to sacrifice any target artifact creature and that creature’s controller searches their deck for a non-creature artifact. I originally thought it would be a good tech to get rid of Darksteel Colossus and Blightsteel Colossus, but then I happened upon this:
along with this…
Meaning all cards you control are indestructible, and are both able to be cheated in with Dagsson. Myr Turbine is also often used since it throws an artifact creature into play, Brittle Effigy for removal, Howling Mine and Font of Mythos for draw power, and so on.
The deck is supposedly able to win by turn 6 or 7. The list I’d recommend taking a look at (though expensive) is here.