What are Riggers and Contraptions in MTG and how do I assmble them? (Steamflogger boss question)
Update: It is now the future. We now know what this mechanic is thanks to Unstable!


Contraptions aren't put into your main deck. To play with them, you must build a separate Contraption deck
In Constructed formats, such as Standard-but-with-silver-borders, Commander-but-with-silver-borders, and all-Un-set-Constructed-but-with-Steamflogger-Boss-I-guess, your Contraption deck contains at least fifteen unique Contraptions. The Contraption deck is "singleton," meaning you're limited to only one of each Contraption.
In a Limited format, such as Booster Draft or Sealed Deck, your Contraption deck can contain any or all the Contraptions in your card pool. The fifteen-card minimum and the one-of rule don't apply. You can play whatever Contraptions you draft or open.
Several cards in the set will instruct you or a creature you control to assemble a Contraption. To do this, turn the top card of your Contraption deck face up. Then, put it onto the battlefield under one of your Contraption deck's three sprockets, helpfully labeled Sprocket 1, Sprocket 2, and Sprocket 3.
At the beginning of your upkeep, if you control at least one Contraption, you move the CRANK! counter forward one sprocket (so, from 1 to 2, from 2 to 3, or from 3 to 1). Then you can crank any of the Contraptions under that sprocket. This causes their abilities to trigger. You can put these abilities on the stack in any order. Also, you don't have to crank a Contraption if you don't want to.
How you assemble your Contraptions determines what kind of infernal machine you're building. Load up one sprocket to produce a devastating turn every three turns, or spread them out to make sure you get something every turn?


Taken as a copy paste of the major points for the article detailing them here.

To all you still back in 2012, I hope this was helpful, you just have to wait 5 years or so to play with them.