Intro:
My take on a high power Kozilek deck. The general deck building philosophy of this deck is to play the most mana efficient finishers as early as possible. Since colorless does most things pretty poorly such as tutoring, protection, and drawing cards, I don't explicitly play any combo pieces unless the opportunity cost of playing them are really low. The only advantage colorless have is being able to generate a lot of mana quickly and actually being able to utilize it fully since there is no color restriction. Hence, this is not really an Eldrazi tribal deck. Its more of a generic 9 cmc+ good cards deck.
One of the misconceptions of this deck is that its a late game ramp deck but I'd say its more of a early/mid range deck. Colorless is actually not the best late game because your opponents will often have a lot of blockers to stop your big idiots, have mana open to stop your plays, and have enough time to draw into board wipes. For example: Ulamog has annihilator 4 but if your opponent have 10 token it basically does nothing. Even if you manage to get an attack through, its just 10 damage and I bet your opponent's decks can do a lot more damage with 11 mana at that stage of the game.
Common Win Conditions:
Commander Damage: If you play Kozilek turn 4 or earlier, your opponents will probably still be setting up their board at that time. So they will have their commander + 1 creature at most at this point of the game. Its pretty common to swing for 12 with menace at 1 player and finish them off the turn after with an unlockable effect or 1 sided board wipe. Just caution to hold certain cmcs cards (1 and 3) in your hand for Kozilek's counterspell ability if possible.
Infect and Annihilator: It's also pretty reliable to play Blightsteel with haste or cheating him out with Kuldotha Forgemaster or Darksteel Monolith the turn after playing Kozilek. If you have Inkmoth Nexus, you can also try to look for Flayer of Loyalties with cards like Sanctum of Ugin or Eye of Ugin. You can also look for Eldrazi conscription with planar bridge to pump your Nexus. Similarly, you if can play annihilator Kozilek or Ulamog and swing with them early enough to destroy some lands, they can also be an indirect instant win.
Infinite Mana: This happens sometimes but not super often. You can get infinite mana with Basalt Monolith + Forsaken Monument and have a few ways of tutoring those cards. Moon silver key, Inventor's Fair, and Planar Bridge. I didn't really play any other tutors because they are too mana inefficient even for this deck, and the previously stated cards are cards you'd play in this deck anyways. Once you get infinite mana, you want to destroy your commander with your lands or even your own spot removals so you can wheel as many times as possible to get an overwhelming board state + potentially killing 1 or 2 players or have an extra turn spell. If you really want to increase your combo potential, the lowest opportunity cost card you can add is Rings of Brighthearth. It combos with basalt monolith and a lot of random mana rocks in this deck + voltaic key. Worst case you can leave it in hand for Kozilek since its 3 cmc. I wouldn't play any other combo cards personally because they are dead draws most of the time. Another incidental combo in this deck is sensei's divining top + ugin + mystic forge but this basically never happens since its a 3 card combo and you have very few tutors. If you just so happen to get those in your wheel then its an actual instant win. You draw your whole deck ->assemble infinite mana combo -> big board state -> 1 sided board wipe -> extra turn.
To end, of course all of these scenarios are ideals but the most common aims. In an actual game you'd have to make judgement calls based on what your opponent is playing.
Mulligan:
The general idea is to mulligan for mana rocks + 2-3 lands that will equal to around 7~ mana generation. In my testing, this ensures that you will be able to play Kozilek on turn 4 or earlier. Although this might not be the best play but it becomes an option. You can Milligan to as low as 5 cards to try to fulfill this mulligan. This is acceptable because Kozilek will draw your hand back after you cast it and you rarely want to cast other spells besides ramping early game unless you have left over mana. The other big mana cards in your hand is basically a brick until you have ~10 mana anyways. If you find yourself casting other random spell like mystic forge turn 3 you're probably not in the best spot in terms of ramp. So having 5 mana cards + 3 other cards in your opening hand is often the same as having 5 mana cards.
Common Cards That Were Excluded
Scorched Ruins: Its a temple of the false gods on turn 3 but the potential loss is too high. If you are playing a deck of this power level, it wouldn't be out of the question for your opponent to destroy important lands. 1 for 3 is too high of a risk.
Jeweled Lotus + Lion's Eye Diamond: These cards both sound good in theory since the commander is so expensive but what ends up happening a lot of the time is that they will do nothing until you have 7 mana exactly. Unlike mana vault or grim monolith, it can't help you cast your other big 4+ cmc mana rocks faster. You only cast your commander once or twice at most since you have so many other big mana threats. So what ended up happening in testing was that they are only good in opening hands that are already really really good. Otherwise if I draw it later they typically become dead draws. Being able to fully wheel with Lion's Eye Diamond is nice once in a while but more often than not you end up really not wanting to discard that 1-2 really good cards in your hand (Ex: board wipe or extra turn spell or combo piece).
Rings of Brighthearth: This card has a lot of incidental combo potential in this deck, it is probably good enough to include in the main deck. At worst you can copy some pretty useful effects. I just haven't gotten around to testing it enough.
Mishra's Workshop: Its good. You can include it if you have it. I just didn't because it cost more than the entire deck.
Cards You Can Cut
They are generally filler cards that might be useful in a specific scenario or when you are behind but is generally cut worthy if you want to play other cards.
Discrete Reality: It's mainly used for the recursion part. You can recur a combo piece since most of them are odd cmc, and sometimes a creature if you are lucky.
Palantír of Orthanc: It's a colorless phyrexian arena + card selection, it's nice if your early plays are disrupted and you can't summon Kozilek. Colorless draw spells are generally very costly so any semblance of "normal" cost efficiency is good. You're opponent probably won't choose mill since there are so many high cmc cards in the deck. I personally also think its also wrong to ever choose mill in general lol. Phyrexian arena is not good enough that you'd want to risk losing a chunk of life to deny 1 card per turn.
Crawlspace: If you are behind you might be able to sit on this + a wurmcoil or any 1 big creature for a while. So its a sketchy propaganda sometimes.
Any utility land: The best lands are the 2 mana generation lands, lands that tutor, lands that grant combat keywords or modifiers, inkmoth nexus and the scry lands. Everything else you can cut if you want for other utility lands. These are just what I found to be the best ones. Although there is an argument to play at least 2-3 basic lands for assassin trophy/path to exile but up to you.
