This is not the most serious deck I’ve ever made.  This is a tribute to the most serious deck I’ve ever made.

http://tappedout.net/mtg-decks/one-drop-edh/

In reality, it’s more of a thought experiment than anything.  “Is it possible to build a functional EDH deck where the CMC of every card (excluding the general) is one?  After some intense theorycrafting, I’m willing to go as far as to say yes.  Yes it is.  It won’t be tearing up the tables any time soon, but I can easily see this deck stealing some games.  The key is in smart resource utilization.  Due to the restricted card pool, I’ve made the deck five colors.  You could probably get away with a Naya, Bant, or RUG list, but each color brings some extremely important pieces to the table, so I think five-color is probably best.  Note that the general is only for show, as this is a 1 mana CMC deck, and casting a 5-drop would be cheating.  I’ll highlight a few important card choices below.

[card]Spell Burst[/card]: Your one way of interacting with the stack, and a surprisingly powerful one, if you have enough mana.  Be aware that continually buying back this spell has the potential to generate a lot of hate, so be sparing with it.

[card]Whispers of the Muse[/card]: This is the spell that rewards you for holding up mana for Spell Burst all the time.  It also lets you keep up in card advantage with the other decks at the table.  Never, ever cast this without buyback.

[card]Mikokoro, Center of the Sea[/card]: Yes, it gives a card to everyone, but you need that card way more than everyone else.  A fine backup when you don’t have access to Whispers of the Muse.

[card]Wurmcalling[/card]: This isn’t so much a finisher as it is a way to keep generating pressure.  Wrath effects are all over the place in this format, so being able to create tokens that can trade with titans without actually committing a card to the board is invaluable.  Also note that making 1/1 tokens and feeding them to a [card]Skullclamp[/card] can be a fine card draw engine.

[card]Land Tax[/card]: This is the engine that glues the rest of the deck together.  In order pony up for those X spells and buyback costs, you’re going to need a lot of mana.  This gives it to you, in spades.  In the early game, this is the first card you tutor for, every time.

[card]Weathered Wayfarer[/card]: Easily the best creature you can drop on turn 1, this has the delightful advantage of letting you find your important nonbasic lands, as well.

[card]Skeletal Scrying[/card]: It’s not repeatable, but it’s good for a burst of card draw when you’re running low.  Sometimes you need efficiency over repeatability.

[card]Breakthrough[/card]: Similar to Skeletal Scrying, this will function as a wonky, overcosted Opportunity most of the time.

[card]Saving Grasp[/card]: Since you lack the kind of robust recursion engine that other decks have access to, it’s important to have ways to protect the creatures you commit to the board.  Save this for important ones like [card]Dragonmaster Outcast[/card] and [card]Figure of Destiny[/card].

[card]Black Vise[/card], [card]The Rack[/card]: Without access to powerful combo pieces or bomby creatures, you’re going to have to win most of your games by grinding down your opponents to zero.  While they only hit one person, dropping a turn 1 Black Vise against the control player can make your job much easier, and a lategame rack can really put the hurt on an opponent who’s left topdecking.

[card]Planar Guide[/card]: It’s an instant-speed answer to enemy token swarms, and one of the few wrath-ish effects that you can find at 1 CMC.

[card]Rolling Earthquake[/card]: This is a genuine wrath effect, one that has the delightful side effect of nugging the entire table, too.  Not that this is the “rolling” version – it hits fliers.

[card]Red Sun’s Zenith[/card], [card]Banefire[/card], [card]Devil’s Play[/card], [card]Bond of Agony[/card]: Fireballing opponents out of nowhere is what this deck does best.

Now, note that I haven’t actually put this deck together and played it, yet.  It looks interesting enough that I might just give it a try one of these days, though.  Feel free to give it a shot yourself, and if you do, let me know how it goes.  Also, let me know if there’s some 1 CMC gem that I missed!