[Magic Duels] Lifeless Wastes

This is a Colorless Eldrazi deck with the emphasis put on flavor rather than playability so keep that in mind when looking at the list.

Depending on what you draw it might play a bit slowly although the possibility for a quick ramp are there. In the long run, assuming you get there, it should win out over most other decks due to its large creatures and game-winning bombs (i.e. the two Eldrazi Titans).

-=Creatures=-
2x Eldrazi Mimic: Okay as an early blocker/attacker, where it really shines is in the mid- to lategame when 5-drops and upward give it a sizeable stat boost and allow it to herald their coming by swinging for usually 5 or more on the turn you played them.
2x Matter Reshaper: A decent 3-drop, it, too, can serve as an early blocker/attacker although its main function really is just the possibility for ramp (by getting a waste on the battlefield once it dies) or at very least the card draw with which it replaces itself.
2x Thought-Knot Seer: This fantastic 4-drop with a decent body allows you to not only look at your opponent's hand to see what they have in store for you (great for planning your next moves), it also gives you the power to effectively take one of those out of the game. The downside here is that the opponent will get to draw should it die but this isn't enough to outweigh this card's benefits.
4x Warden of Geometries: In order to get as quickly to the magical 5-mana mark and beyond this curious Mana Dork suits us fine. Its vigilance means that, provided it can come through alive, it can attack and then still be tapped for mana in Main Phase 2 or even the opponent's turn. The 3 toughness also allow it to block many of this format's smaller creatures or deter them from attacking in the first place.
2x Reality Smasher: Does its name proud and smashes your opponent's reality when it comes out of nowhere, hastily attacks and tramples through any smaller defenders. Its ability makes sure that your opponent either has to dearly pay extra for removing it or can't remove it in the first place (should he have no other cards in hand except for the removal).
3x Walker of the Wastes: The heart of this deck and partly responsible for its name, this terrifying creature will usually enter your side of the battlefield as an 8/8 trampler and only grow stronger as the game goes on. If your opponent doesn't deal quickly with it then it can often single-handedly win you the game in no time at all.
Quick anecdote: My opponent once faced one of these late in the game and even his massive 12/12 Werewolf of Ancient Hunger couldn't pose a threat to its rampage.
1x Oblivion Sower: Useful for exiling some of your opponent's cards and possibly ramping a bit by stealing his lands, this 5/8 6-drop can hold its own on the battlefield and even survive a small army of weenies when attacking on his own.
2x Endbringer: Not quite as powerful as its name suggests, it is nevertheless a good fit for our deck as its quasi-vigilance and versatile abilities (damage, disabler, card draw) allow you to be a bit more tactical in your approach than the simple “attack, attack, attack” that the other creatures so far mostly favored.
1x Ulamog, the Ceaseless Hunger: What even needs to be said about this legendary Titan of the Eldrazi? He is not only an invincible 10/10 creature, it also exiles two of your opponent's permanents (could be troublesome creatures, enchantments or his only two, say, blue lands)
regardless of whether or not it is counters and once it starts attacking it makes sure that those two permanents it exiled earlier won't stay lonely for long.
Incidentally, an Oblivion Sower following an attack of Ulamog will provide you with all the mana you will ever need. Not that you normally need any at all anymore at that point.
1x Kozilek, the Great Distortion: Upon leaving your hand to enter the battlefield this other Titan lets you draw up to seven cards, providing you with an enormous card advantage simply by virtue of gaining more resources. After that its monstrous 12/12 body ensures that only two big, mana-intensive blockers can hope to take it down. And should your opponent hope to get rid of him via mere removal spells you can usually make sure that this doesn't happen by discarding one of your freshly drawn cards (since CMC 2 to 6 are numerously present in our deck).

-=Sorceries, Instants & Others=-
2x Alchemist's Vial: An acceptable turn 2 play, this artifact immediately replaces itself by letting you draw a card and later on allows you to either stop a nasty creature from attacking or an annoying one from blocking. On occasions this ability can mean the difference between victory and defeat.
3x Warping Wail: This 2-mana Instant spell is reminiscent of two-color spells in its versatility. It allows you to either counter a sorcery (boardwipes such as Planar Outburst, removal like Declaration in Stone or burn à la Rolling Thunder are nice targets), exile one of the many <1/x or x/<1 creatures of this format or create a 1/1 chump blocker/mana accelerator. Definitely useful in a variety of circumstances.
3x Spacial Contortion: Decent removal for 2 mana, this card already kills a lot creatures (including some invincible ones such as Insidious Mist) and, when combined with Warping Wail, kills even more. Alternatively, it can also be used to buff a strong creature of yours in order to deliver those last lethal points of damage. If used for that purpose it should be checked whether or not the x/-3 part brings your attacker within the range of your opponent's removal/burn spells, should they still have mana open.
4x Seer's Lantern: Good for getting you more mana quickly and, should you have two more sources of mana open, scrying to get to the cards you need faster. Flavor-wise kinda inverted but we simply need this.
2x Titan's Presence: Acceptable removal that not only kills but exiles its targets but with the downside that you need a creature in hand that is at least as powerful as the target.
2x Meteorite: Another mana acceleration card with a relatively high cost but the small benefit that it can deal some damage to a creature or player.

-=Land=-
22x Wastes: Nothing fancy here, just the basis for Walker of the Waste's might. Given that we want to get to as much as 10 mana as soon as possible the number seems appropriate.
2x Ruins of Oran-Rief: An okay non-basic land that, while slow, allows you to occasionally buff your creatures after you played them.

Ideally, your starting hand would look something like this:
2x Wastes
1x Ruins of Oran-Rief
1x Warping Wail
1x Seer's Lantern
1x Endbringer
1x Walker of the Wastes

That hand would allow you to play a Walker of the Wastes on turn 4 and a Walker of the Wastes on turn 5, putting some serious pressure on your opponent relatively early on. The downside of this would be that extremely aggressive decks would have had up to three rounds to attack you but if they cannot immediately get rid of the Walker then you should be able to quickly more than make up for that. Just keep in mind that time is generally on your side with this deck as you get closer and closer to being able to bring out one or both of your Titans.