As a note, just as before, these numbers are all based on the full set, not trying to discount for playability (that will come a little later, if there's time - but it may well be that people will just have drafted a bunch by then). And in every case, what I am presenting is the per-draft number, i.e. the average number of cards fitting a given description which you would find total in the 24 booster packs opened in any given draft, adjusted for rarity.
First up, let's look at the Eat-Bounce-Trade Chart, the concept of which I described in my last set review, here.
In Origins, this kind of analysis showed us that 2 drops were going to be good: there just weren't very many creatures that ate them until you hit LOTS of mana - basically nothing was there for 3 mana, and not much for 4, either. There just weren't good defensive creatures - you had to settle for playing other creatures to trade, at which point... well, you needed 2 drops. Of course, throw in renown, and few benefits for going big, and the writing was on the wall.
Here, things are much less clear. There isn't any clear spot like that: things just keep getting bigger and bigger. There's also a decent number of cheap high-toughness creatures, from a 2 mana 1/4 to a */5 to an 0/6... just playing 2-drops is going to not be so hot. By 4 CMC, you're going to have 46 cards per draft (or almost 6 cards per player per draft, on average) which can eat bears. This is enough that it will be pretty reliable to shut down the aggro player. Which means that the aggro decks are going to need to be a bit more sophisticated in order to work.
This brings me to the biggest thing I see about this format: for quite a while in limited, and this was especially true in Origins, it's been quite a good strategy to navigate picking the best card available in your colors, with some nuance in staying open enough to get into the right colors and for e.g. curve considerations. But more or less, you're just taking the best overall card. In this set, I don't think that's going to be the case. You really need to be building a deck. There will be lots of cards which are quite good in the right deck while being totally unplayable in others - even in the same colors. With this in mind, let's go to:
LandfallFor everyone's favorite returning mechanic from the original Zendikar (I say this tongue-in-cheek, because it made for super fast, aggressive games, but apparently WotC's market research showed that it was actually the most popular mechanic; in this format, it is probably going to be tempered a bit more than in original Zendikar) is back with... well, not with Ajani Vengeant, but it's back. How much of a thing is it? 41 Cards per draft (5 per player on average, but I will note that with everyone going for their own deck, if you want the 'landfall deck', you can get more). Enablers? Just over 8 per draft - which is only one per player (and some of them are bad), but on the other hand, you are naturally going to have enablers in just having lands. This tends to be aggressive and beatdownish again. I don't think there's really going to be a landfall deck, but your more generic aggressive decks will like these cards, and if you have enough, the enablers do start to go up.
AlliesAllies again tend to be on an attacking plan. They have a similar trigger, on EtB of something you can do normally at sorcery speed, which wants the action to be on your turn. In terms of numbers, there are 50 of these per draft - a bit more than landfall - and 22.5 which care about allies. You probably want at least 4 or so of those enablers before you consider yourself an 'ally deck', and of course some of these are better than others - vigilance is fine but not great, but pumping your team or giving them Menace or Double Strike is pretty fantastic, especially given that these decks tend to want to fill the board with creatures. Given the number of allies around, and that you're largely wanting to go for 'your deck', you can probably get quite the critical mass of the allies - it's less clear that you can get the key bonuses, but there are enough that most tables should support 2-3 "ally" decks, it seems. A note on colors: white has no eldrazi/colorless, and thus an overload of allies. Blue has very few. Just something to keep in mind...
ColorlessThe Eldrazi are colorless, and that is a theme of the set. There are a number of cards which care about colorlessness. How prevalent is it? There are 99 colorless cards per draft, including 66 colorless creatures. That is a LOT, especially when you consider that white has none, and some of the more aggressive decks will be interested in few colorless guys, if any. 8 creatures as a part of a total 12 spells is a good average rate, and if we assume two players don't want any... that takes us to 11 creatures and 16 total spells, which means if you have those colorless matters cares, you can really, really be in business to enable them. There are only about 15 cards per draft which care about colorlessness, but they're well-supported.
ScionsThere are 19 cards per draft which make Scions, which make a total of 28.4 Scions. These largely overlap with the previous section, but these are something to keep in mind.
Exile/ProcessThere are 18 processors per draft. They are supported by 28 exile cards per draft, plus 16 Ingest creatures, for a total of ~45 potential enablers. Some of these aren't very good, but, similar to the Exploit deck from Dragons, there definitely seems to be support here, if you are looking for it. In fact, this shows up a good bit more than that exploit theme. At the same time, the ordering needs to work out (exile before process) in order to get it going, so you definitely don't just want to pick tons and tons of processors - there is a limit, kind of like there was with Delve. In any case, especially with the more expensive such cards, you can support this if you want to, but keep an eye out that you're picking your spots.
Life GainThis sub-theme is based on BW. We have 10.2 cards per draft which care about this, with 17.7 ways to gain life, including 10.1 ways to do so repeatedly (none of this is counting lifelink). This isn't really enough to be a major thing you can count on every time. Some drafts will certainly not have this kind of player, and definitely don't expect more than one per table - indeed, an actual life-gain based deck will, I think, be pretty rare (though not unheard of). Instead, a few of the good cards as a mini-synergistic package which doesn't cost much is the way to go on this one.
AwakenThis mechanic isn't terribly self-synergistic, as if you have lots of Awaken cards, it's going to be hard for you to play them all "for value", as that will end up being quite the high curve. On the other hand, there are only about 17 of these per draft, and about everyone will like them, so I don't actually expect it to be a deck, but everyone should get a pretty good number. They're pretty evenly split between 3/3s and 4/4s (slightly more 3/3s) with an uncommon that makes a 2/2 and a mythic that makes a 6/6. These are, for the most part, ranging from 5 to 7 mana, so keep that in mind when you're looking at your creature size chart. The haste aspect is also something to think about in the late game.
FixingConverge, and to some extent allies, asks you to make lots of colors. How realistic is this? There are about 15 fixers per draft, which is just under 2 per drafter. Given that lots of decks will want to be 2 colors, and that most of the fixing is centred in green.... you can pull off multi-color decks, but you really need to do work in prioritizing to get there, especially as those rare lands are not just whatever colors you want. Keep in mind that Evolving Wilds will be sought by landfall decks too, so don't expect to go too hard. A splash should be a lot more possible here than in Origins.
I might also talk about Expeditions here. I didn't calculate them, or any foils, in any of my calculations, as I can't get solid numbers on what frequency they appear. If anyone can point me to somewhere that has this, I could incorporate it in the future. At any rate, it shouldn't make a huge difference.
General Format Thoughts
Mana SinksUnlike Origins, there are lots of mana sinks in this set - by my count, about 33 per draft. That is enough that you can pretty much have one if you want. I think this is good, as it lets you smooth some things out. Obviously, some of these sinks aren't good, but I expect most decks to have a couple.
LandsBetween huge Eldrazi, Awaken, landfall, mana sinks, and spell-lands (and extra colors), I think you're going to want to run 18 or even 19 lands most of the time. On the other hand, the aggressive ally decks may really want to lower that curve and run 17 or even occasionally 16. Don't be afraid to play lots of lands, but definitely you need to be attuned to what your deck wants.
SpeedI have already alluded to this a little, but I expect this format to be a LOT slower than Origins, and indeed, below-average on speed. Aggressive decks will exist, but you really need the enablers for them - the finishers, mostly. The defensive decks... you don't really need lots of 2 drops, but 0-2 would be nice. Definitely you can't take all day, or you will get run over. But in general, I think I would rather be the ramp deck here than the
Finally, in general, with more specific decks and archetypes, even within and across colors, this set will, I think, play more like cube. That means you want to focus on making a good deck more than good cards, and sideboarding is going to be a really big deal, as you want to tailor your deck for the matchup you're in.