Ashnod's Altar: Enabler. Sacrifice outlets are good in EDH. Especially when your commander says draw 4 cards on cast. Throw in infinite mana to win on the spot. I have tried cutting this many times and always find that I still want it. This is very useful when you have infinite mana as it is a repeatable sacrifice outlet so any card in library can be looped an arbitrary amount of times. Without this, it is often difficult to win on the spot with infinite mana.
Azor's Gateway
: Acceleration, Enabler. This card is a good way to dig through your library and ditch some of the cards that occasionally result in a brick hand of really high CMC stuff and has a ridiculous ramp potential if it ever flips. Goes great with Unwinding Clock.
Clock of Omens: Acceleration, Enabler. This card does everything. Primarily used as an acceleration piece, this also works as an enabler for greater shenanigans such as untapping stuff that doesn't untap on it's own and even tapping down certain stax pieces so that they do not hinder us. You will see this mentioned many times throughout this primer.
Doubling Cube: Acceleration, Combo. From 7 mana onward this is acceleration with progressively more upside as you throw more mana at it. Goes hilariously well with Clock of Omens and Paradox Engine to get absurd amounts of mana. One of the best ways to continue casting Kozilek once he hits the 14+ cost. Goes really well with Horizon Stone.
Forsaken Monument: Acceleration, Combo. The extra mana that this produces is great and it also just happens to go infinite with Basalt Monolith. Probably the best replacement for Paradox Engine that this deck will get any time soon.
Horizon Stone: Acceleration, Enabler. This is a way to stockpile extra mana and ramp as well as just making ludicrous amounts of mana with Unwinding Clock.
Inspiring Statuary: Acceleration. This is a great acceleration piece most of the time but against decks running Stony Silence (the absolute worst possible card for you to see while playing this deck), it might as well be the Holy Grail. Improvise is not an activated ability so you can use this to get to something like a Karn Liberated or Ulamog, the Ceaseless Hunger and actually play the game.
Lion's Eye Diamond: Acceleration. Definitely a situational acceleration piece but in the correct situations, it is one of the best you could ever hope for. Mainly used to cast Kozilek from the command zone and immediately replace the cards you ditched to use it. Turn 1 to 2 Eldrazi Gods are not uncommon with this. Also works great as a free untap for Paradox Engine or just a regular Mox with Inspiring Statuary. Of all the high dollar cards in this list, this is one that I would recommend over all of the rest.
Mindslaver: Interaction, Payoff. Quite possibly my all time favorite card thanks to this deck. I could go on for pages with hilarious stories of ridiculous ways this card has killed my opponent and won me games that were not possible to win with any other means but anyone who has been hit by a Mindslaver before knows that this card is the most devastating effect in all of mtg short of an effect like Door to Nothingness. Goes great with Rings of Brighthearth to take multiple players turns. Also, as mentioned previously, probably your best card against dedicated combo decks.
Mirage Mirror: Acceleration, Interaction, Combo. This is an interesting clone piece that turned out to be incredibly good in practice. It shines when you can use it multiple times in response to its own ability (i.e. activate targeting your Grim Monolith, maintain priority, activate targeting an opponents Necropotence. Allow the first ability to resolve, spend some life into the Necropotence, and then it becomes a Grim Monolith that won't have the downside of not untapping normally because it will be a Mirage Mirror again at end of turn).
Moonsilver Key: Enabler. I wasn't expecting colorless to get a decent tutor but I am not going to argue.
Paradox Engine: F
Relic of Progenitus: Interaction. It is graveyard hate that can cycle itself. What else could you hope for?
Rings of Brighthearth Enabler, Combo. Primarily used for its win the game immediately combos, this can just be used as a great value piece. Does everything from getting an extra draw off of cycling a Blasted Landscape to taking multiple players turns with a Mindslaver to just making an arbitrarily large amount of mana and winning the game.
Semblance Anvil: Accelaration, Combo. One of the best acceleration pieces in the entire deck with the downside of losing an extra card if it gets destroyed. Whenever possible, imprint an artifact creature to get the -2 mana discount on both artifacts and creatures. Combined with Paradox Engine allows for some ridiculously easy "storm" turns and is also an option for the Spine/Krark Clan combo. Do not underestimate this card. I even intentionally added a few more artifact creatures to the deck specifically because of how good they are with this card.
Staff of Domination: Interaction, Combo. Mainly used for it's "win the game" with Metalworker and 3 artifacts in hand. Also works with a Clock of Omens, Sculpting Steel as a second Staff and an artifact that taps for 3+ mana. Outside of that, it is a decent mana sink with some reasonable forms of interaction stapled onto it.
Static Orb: Stax. Pretty self-explanatory. Errata'd to only work when untapped so combine with a Blinkmoth Well/Clock of Omens to make it one sided.
Strionic Resonator: Enabler. Goes hilariously well with Eldrazi cast triggers (or attack triggers, Annihilator 8 usually says defending player concedes in a salty manner). Also just happens to go infinite with Paradox Engine and at least 3 mana from nonland sources (and a spell to trigger then engine obviously). Engine/Resonator is the most common turn 1/2 infinite for this deck to pull off due to the relatively low mana investment.
Tangle Wire: Stax. Again, should be pretty self-explanatory. Just make sure to order the triggers on your turn so that it removes the counter first. Also goes great with stuff that doesn't care if it is tapped such as Ashnod's Altar or itself as one of the three assuming it makes it back to you. Usually the best stax piece to accompany an early Eldrazi God because it prevents your opponents from using most sorcery speed interaction or throwing out some Annihilator fodder before they get hit.
Tormod's Crypt: Interaction. Graveyard hate is graveyard hate. Not much that needs to be said. Can also function as a Mox with Inspiring Statuary in play.
Torpor Orb: Stax. Stops a few cards in this deck while entirely crippling certain strategies. Also just happens to stop a ton of the most annoying cards for this deck to see (Bane of Progress, Reclamation Sage, Zealous Conscripts, etc.).
Unwinding Clock: Enabler. Mainly used for the free untap on stuff that does not untap on its own. Also goes great with anything you can use mana to do on an opponents turn as well such as Eye of Ugin, paying the rest of the cost on Mindslaver, drawing cards with Mind's Eye, sacrificing Burnished Hart, and much more. My favorite use other than the artifacts that don't untap on their own is Kyren Toy and Coalition Relic to put a ton of charge counters on them to ramp you on your next turn. Just think of it as the artifact version of Seedborn Muse and it should not be hard to justify it's inclusion.
Winter Orb: Stax. See Static Orb.