Arcum Dagsson commander deck, with 10-card sideboard. This deck is tuned for more-competitive commander groups, and especially for 1v1.
Use Arcum on fodder to get whatever you need from the toolbox that is the deck -- if they're playing a combo with an activated ability you get the Pithing Needle, if they're going to do infinite etb triggers you get the Torpor Orb, etc. If you don't need any defensive cards or Spine of Ish Sah the first time you resolve Arcum's ability, I strongly recommend getting Myr Turbine (it'll pump out fodder for more Arcum activations) or, if you have the Turbine in hand or on the field, get Unwinding Clock or Thran Dynamo.
Explaining My Custom Card Categories:
Cheats: Things that let you put something from your hand or the battlefield on the board for little/no mana, at zero cost to your board-state; or things that let you untap multiple times and play on anyone's turn.
Digging: Things that let you draw or otherwise put cards from the top of your library into your hand and/or scry or otherwise rearrange your deck's top cards.
Fodder: Things whose primary purpose is either to be sacrificed to Arcum or to make things to be sacrificed to him.
Lands: Lands that have no non-mana ability as well as Arcane Lighthouse, whose non-mana ability is only useful against a specific set of creatures/deck types (other categories contain lands that do what the category does).
Lattice Wincons: These cards can win you the game thanks to Mycosynth Lattice turning everything into artifacts: Nevinyrral's Disk and Darksteel Forge by destroying everyone else's permanents, Blasting Station and Summoning Station by infinite pings (thanks to Lattice, Summoning Station's Pincher tokens are now artifacts and sacrificing them to Blasting Station triggers Summoning Station's untap ability.)
Other Wincons: Other ways to win the game -- technically most of the artifacts in the deck count as wincons too, when used with Tezzeret and/or Master of Etherium, and the creatures here can be used as Arcum fodder in a pinch (and Tezzeret can be used as ramp or as a tutor, and Ugin as removal), but these are cards that can often just win you the game by themselves (or in combination with Crucible of Worlds, in Strip Mine's case), or turn your mass of little things into a bigger, more threatening army.
Protection: Things that are chiefly here to protect you and/or your permanents. Includes Kozilek and Blightsteel because their main purpose these days is to make the deck impossible to just mill to death (I hate Annihilator and Infect, so I try not to win with them in casual games.)
Ramp: Things that let you cast bigger things faster (mana rocks and cost reducers.)
Recursion: Things that bring other things back from the Graveyard.
Removal: Kills things.
Tutors: Things that search your library for certain cards. These may put them onto the battlefield, but you still pay their mana cost and/or sacrifice multiple cards to do it.
Xeroxing: Cards that make or become copies of other things as needed. May be cheat-y.
Other things this deck can do:
Prototype Portal with Lotus Bloom imprinted on it alone is pretty sweet, but if you add a Voltaic Key and all possible Xeroxes of that key (assume Saheeli's Artistry was exiled after use; otherwise, for each extra use of Artistry to copy a Key add n+1 copies to the end result and 1 more artifact mana to the requirements), Tezzeret's +1 (untap Portal and a Key), 5 mana from reusable artifacts that can be untapped each turn with Unwinding Clock, and said Clock, and you can generate 5n + 2 copies of Lotus Bloom per turn cycle, where n is the number of turns in the cycle (yours and everyone else's).
Memnarch can steal anything and everything, and if you have Lattice out it cuts down on the cost to steal an otherwise-non-artifact permanent.
Mindslaver lock - In addition to the Mindslaver this requires an untapped Academy Ruins and 12 mana; or 12 mana, an untapped Buried Ruins, and Cruicble of Worlds; or 10 mana and having imprinted the Mindslaver on Prototype Portal (dangerous!). Play the Mindslaver, take control of your opponent's next turn, then put it on top of your library or into your hand if you went with either of the land plans, and if you're using Buried Ruins + Crucible, play the Ruins from your graveyard.
Not-Necessarily-Intuitive Card Interactions:
Even though Mycosynth Lattice makes everything colorless in every zone, it only makes permanents on the battlefield into artifacts--until they are on the battlefield they will remain only whatever they say they are on the card, so you still can't tutor for something or cheat it into play if you couldn't before the Lattice came down.
Tezzeret's ultimate will unequip the Lightning Greaves and Manriki-Gusari from whatever they're attached to and they will be unable to reattach until your next turn, since they become a creature too.
As a reminder, Tezzeret's ultimate does not give Haste, so if you steal your opponent's non-creature artifacts with Memnarch before ulting Tezzeret on the same turn, the now-creatures you stole or otherwise put on the battlefield that turn won't be able to attack or use abilities that have the tap symbol until they stop being creatures again.
Tezzeret's ultimate also doesn't make artifacts that enter the battlefield after it resolves into artifact creatures, so ult before you get any mana rocks that turn!
