December 19, 2016: Cut Tracker for Arbor - it's probably going to be better most of the time. Cut Sneak for a Bonfire; perhaps I'll warm up to it (pun intended)... :p
Comments on specific cards (that I tried to order by CMC):
Cloudpost/Glimmerpost/Forest/Taiga/Windswept Heath/Wooded Foothills: Mana sources. Red's included mostly because I liked Modern Tron a lot less after Ugin's Eye got poked out and I still had (have) my Groves; this deck has a certain toolbox-y feel to it that Tron never had, which I also like. Of course, the current version doesn't run groves... but whatever.
Eye of Ugin: Part One of this deck's inevitability. It's the land that stops us from fizzling mid-game, and it lets us tutor whichever Eldrazi Titan is most relevant to the game. Sometimes, it synergizes nicely with Sneak Attack, allowing an Emrakul attack each turn.
Karakas - Part Two of the deck's inevitability (bounce Eldrazi for their cast triggers; specifically Big Emrakul for infinite turns) that also happens to be a great silver bullet against anything trying to use big, obnoxious legendary creatures.
Cavern of Souls - Usually names Giant (for Primeval Titan). I often find myself Crop Rotating for it at the end of an opponent's turn. If they counter the Crop, then I can drop Titan with one less counter to worry about; if they don't, then an uncounterable PrimeTime is headed their way. It's also an untapped colorless source, which is relevant for early-game Warping Wails.
Bojuka Bog - Wonderful silver bullet; with Crop Rotation, it gives this deck a lot more game (G1 and beyond) against graveyard-centric strategies like Reanimator, Dredge, and even Lands. It comes out when it's not really impactful, but when it's good, it's amazing.
Glacial Chasm - Another great silver bullet. Though the cost is quite steep, it's much appreciated in several matchups (like Elves, Burn, Empty the Warrens decks, and Infect), or when you just need a few extra turns to get online. I could see myself swapping this with the sided Maze of Ith, but I currently lean against that.
Vesuva - Usually copies Cloudpost, but it can sometimes copy Bojuka Bog or Glacial Chasm when one just isn't enough. Less commonly, it can copy an opposing green source or it can be a Cavern naming Eldrazi.
Thespian's Stage - Run over the third Vesuva as Vesuva can be clunky early on, and this can "protect" legendary lands when it's untapped (or even itself, if it copies a basic in response to being Wasteland-ed). Occasionally can steal someone else's Dark Depths, but it usually just turns into another Cloudpost. It can also, of course, combo with a Dark Depths of my own (should I chose to run it).
Maze of Ith (SB) - Sometimes, this card can win the game on its own, eternally fogging a tempo deck's threat and buying you way too much time. It's less of a silver bullet than Chasm is, though, so it's in the side. Then again, that could be bad logic, and perhaps it should be in the main :p
Dark Depths (Maybe) - It can surprise people and win out of nowhere, but it's pretty clunky when it's in the grip, and we can't abuse it quite as much as the dedicated Lands deck can. It's possible that I should include this over some other card, but I'm not quite sure.
Dryad Arbor (Maybe) - Makes Zenith better, and can save a creature from a Liliana Edict. Then again, it turns a ton of stuff into a Stone Rain, so I'm iffy on this one.
Tabernacle (Maybe) - I mean, I could get a thousand bucks at some point, but I don't have that yet, so I'll make do for now. It's probably a good card, too, and I'm definitely not going to need more than one given the nature of the deck, but if/when I do get one, I'll still need to think for a good long while about where I'm slotting it in :p
Crop Rotation - One of the toolbox-y elements of the deck. It can "save" a Cloudpost from getting Wasted, it can turn a land into a silver bullet, or it can just find a locus. It's a 4-of 'cause I'm not running cantrips and the deck appreciates the redundancy.
Expedition Map - Less toolbox-y than Crop Rotation, but it doesn't need a land to sack, and it lets us make the decision of which land to grab later. It can grab any of our 1-of lands (though it doesn't grab Bojuka Bog very often), or it can grab another Locus. Currently, it's a 3-of.
Pithing Needle - Usually names Wasteland, though it can name plenty of other cards just as well. I never know what number is correct to run, so I've settled on two for now - it's possible that the number is too low or too high, though I've never quite had the nerve to cut it altogether.
Sensei's Divining Top - The best non-blue card selection in the entire game (that I can think of right now, anyway). We're not as good at abusing it as Miracles is, but card selection is still card selection, and it's really good, repeated card selection.
Veteran Explorer - Plays a lot of mind games; do they want to ramp us by attacking, or do they want to stand back and give us more time to develop our board? It's naturally at its best against basic-light decks like Eldrazi, but it's still good against decks with basics... Usually we appreciate the ramp more than they do, anyway. It's a 1-of because we're not Nic Fit and we're only running so many basics ourselves (3 is the number I've settled on for now, though it's possible that's too low). It's at its worst against creature-light decks, which is probably not destroying it ever.
Pyroblast (SB) - Good 1-mana get-rid-of-a-blue-thing spell; fights countermagic, Delvers, the occasional Jace or TNN, and more. It's also cute against Painter.
Surgical (SB) - Comes in against decks that abuse the graveyard, like Dredge, Lands, and Reanimator (and against some others that don't, since it's better than some of my other cards against some combo). It's like a Force of Will against many of these decks, and sometimes better. If I'm feeling janky and cute, it's also a way to look through my opponent's deck (though that's pretty bad, and the last time I tried doing that, nothing ever reached my opponent's graveyard anyway).
Candelabra of Tawnos (Maybe) - Good, expensive, never getting reprinted. At least I get to tell myself that, since it loses to Chalice on 1, my non-inclusion of this one isn't the end of the world. Of course, if I ever get into MODO... but then I'll still have to think about where I'm shoving this thing in (and, worse, how many).
Warping wail (2 SB, 2 MD) - Really flexible; all of the modes are relevant. It can stop any of the multitude of important sorceries in the game, as well as stopping any 0-1 P/T creature (it's a very long list of creatures, and I'm sure you know that). It can even be a jank ritual or chump blocker. It's possible that I should jam all 4 of these in the main.
Stronghold Gambit (1 SB, very much a maybe card) - It's the red Show and Tell, stolen straight from BR Reanimator. It's best used against creature-light decks or (funny enough) Reanimator (as most of their creatures are more expensive than the Primeval Titans we're trying to cheat out). It's hilarious, too, and can win many otherwise-unwinnable games, but then again, it's pretty terrible in the wrong matchups (or even in the right ones if they happen to have a cheap creature). Often, it has what I'm going to call the Stifle effect - when people see it, they tend to play around it, often more than they should.
Sudden Shock (Maybe) - Good against Infect, Mentor, Pyromancer, and Delver. Then again, I'm not sure if it's better than the other options and I'm not sure what I'd cut.
Cursed Totem (Maybe) - It's nice against Knight of the Reliquary, Elves, and other creatures with activated abilities, but I'm not sure we need the help. It's always something to keep on the table, though.
Sylvan Library (Maybe) - It's card selection, but it dies to decay, is more expensive than Top, is redundant with Top, and I'm rarely (if ever) at the liberty to pay 4 life for an extra card when nearly every other deck wants to try killing me quickly. Still an option, though.
Melira (Maybe) - Just on this list in case Infect becomes super-insane. It's not the worst matchup, but by no means is it a good one. Infect isn't crazy-popular in my meta so this probably isn't worth it.
Kozilek's Return - A wrath against many decks, at instant speed no less! Kills every creature Wail can and some of what it can't. It's really great against Elves, Death and Taxes, Empty the Warrens, and even Monastery Mentor. We're also more than capable of abusing the back half of the card, letting us make any of the Eldrazi Titans even more devestating than they already are. It's possible I should include more, but then again, it's possible that 2 is enough :p
Tireless Tracker - It's meant to be an in-between between Oracle of Mul Daya (which is the in-between between Primeval Titan and Veteran Explorer) and Veteran Explorer. It can turn lands into cantrips and fetchlands into divinations. It gets insane with Primeval Titan, and it can be a somewhat-early clock if it needs to be. That being said, it might just be a win-more card that should be something else.
Ensnaring Bridge - Mostly here for Eldrazi, but it comes in against Show and Tell decks and Reanimator too. We're not the greatest at getting hellbent, but I'd rather have hate that doesn't die to Warping Wail (Silent Arbiter) and doesn't require us to hold up mana forever (Forcefield). We're more than capable of getting rid of it when we need to, though if we're somehow unable to, we can, in theory, always just bounce Emrakul forever while we roast our enemy with Ugin (though this has never happened to me). If there's better-fitting hate that I'm unaware of, though, I would love to know about it.
Krosan Grip/Reclamation Sage - Artifact/Enchantment hate. Sage is Zenith-able, but it's possible it should just be another Grip.
Oracle of Mul Daya - Speaking of in-betweens, this is the guy underneath the Primeval Titans. When we're not quite at the mana we need to Zenith for a Titan (or just cast it), we can bring in this guy. It's nice card advantage, and sometimes it can win the game. Dies to Swords and Bolt but not to Decay (despite being a 2/2 that therefore looks decay-able).
Sneak Attack - Sneaky, and lets us cheat a bit on mana if we need to, Blood Moons be damned. Best used to drop a Primeval Titan, but dropping in an Eldrazi is nice, too. It's only a 1-of since it's a bit red-intensive, and it's possible that this shouldn't be in here at all. Then again, like Gambit, it sometimes has that Stifle effect.
Mindbreak Trap (SB) - Probably clunkier than it should be, but it's alright as a hedge against decks that cast many spells in the same turn. I have 2 in paper, and this is the sort of effect I want more than 1 of the the matchups I want it in, so it's possible that I want to go up to 2. Then again, it's clunky and I'm never casting it for full price, so maybe it wants to be something else instead.
Primeval Titan - In some decks, this would be the win condition, but that's silly. Here, it's a creature that provides incredible value. Since we're running a few toolbox-y lands, PrimeTime itself becomes a utility creature if it needs to; it can grab Bojuka Bog if a graveyard is scary, it can grab a Karakas to laugh at opposing Show and Tell'd-in Legends, it can grab a Glacial Chasm or a couple of Glimmerposts to help us survive... and this is not only when it enters the battlefield, but when it attacks, too.
Ugin, the Spirit Dragon - Perhaps it's a flavor fail to have Ugin working with the Eldrazi, but I digress; this guy can win games all by himself. Some decks can't beat him, others are left scrounging for one of their few outs. Definitely a good 'walker for the deck.
Ulamog, the Ceaseless Hunger - Usually, this is the Eldrazi I tutor when I'm either facing down troubling permanents or don't quite have Big Emrakul mana. Gets rid of Humility, Blood Moon (if the game is insane like that), opposing Planeswalkers, or lands. Synergizes well with Karakas, especially if Ensnaring Bridge is on the field.
Kozilek, the Great Distortion - If I'm tutoring up this one, it's because I want to draw a bunch of cards. I'm running him over Old Kozilek because this one tends to draw more cards when it's relevant (the difference between going from 0 to 4 and going from 0 to 7 seems pretty big). The counterspell mode is also quite relevant (despite our wacky curve), and people rarely seem to respect that fact that he has Menace. Probably the weakest of the Eldrazi Titans, but then again, he still feels good enough to keep in.
Emrakul, the Promised End - The scourge of Standard is here, but this time she's playing with much more power. Though the floor on this is literally "look at target opponent's hand, then they draw a card", more often than not it wrecks face; it's still a 13/13 flying, trampling Mindslaver, after all. If I'm tutoring her up, it's probably because my opponent has a grip full of cards. While we're not the best at becoming Delirious, Emrakul's cost reduction does come into play often - we're likely to have at least lands and instants in our graveyard, and in long games, especially if our opponent has forced us to discard cards, it's possible that she'll become cheaper than either of the 10-drop Eldrazi.
Emrakul, the Aeons Torn - Part Three of the deck's inevitability. She's only the most powerful creature ever to be printed. If swinging with her once isn't enough, we can try again once we bounce and recast her. If swinging with her isn't possible, perhaps death by Ugin's Ghostfire is an option. It's pretty hard to lose once we've resolved this one, at any rate.
