I know very little about Block Constructed. However it's definitely begun to pique my interest lately. With all of New Phyrexia spoiled much too early, and with Pro Tour Nagoya approaching, the format is ripe for breaking, and Standard has gotten pretty stale. So it's time to focus our attentions on a lesser format.
SOM Block currently is full of intriguing dynamics and shifts; the delicate balance between Phyrexia and Mirrodin is in constant flux. The major battle taking place is between artifact-matters, zero-artifacts, and being-somewhere-in-between. The second major battle is between the mana and the spells that want to be cast. The third battle is between speed vs. power, as is usual in the realm of Magic (somewhat related to battle #2).
Today, let's look at the mana, shall we?
Inkmoth Nexus
This is the defining land of the format. To be fair, it's basically the only land that really does anything. Almost everyone would like to have Inkmoth Nexus for added utility, but not everyone can. Only monocolor decks tend run Inkmoth Nexus currently. Mana fixing in the format is weak, and sacrificing colored lands for the Nexus makes casting your spells awkward (unless you're this guy apparently). Although, there are probably cases where cutting colored lands for one or two Nexuses is justified.
However, if you can run Nexus, it's often worth it. It doesn't even matter what kind of deck you are.
Obviously, Mono-Black Infect runs Inkmoth Nexus—it's an uncounterable source of poison that can only be dealt with at instant speed and can't be blocked on the ground. That's insane! Tezzeret decks are the only multicolor decks that run Nexus because of its synergy with Tezzeret. One good hit with a 5/5 infector can ensure victory from almost out of nowhere.
Mono-white, red, and blue decks also run Inkmoth Nexus because it becomes an artifact for the cost of one mana. Any deck that relies on metalcraft can use Inkmoth to great effect, even if it doesn't win with poison damage. Common metalcraft cards currently in use: Kuldotha Phoenix, Galvanic Blast, Mox Opal, Stoic Rebuttal, and Ardent Sphinx. Inkmoth also has great synergy with Tempered Steel, Kuldotha Rebirth, and Glint Hawk.
Interestingly, New Phyrexia only has three cards with metalcraft: Puresteel Paladin, Dispatch, and Jor Kadeen, the Prevailer. The first two here are interesting and provide strong incentive for putting the pedal to the metal, as it were, in mono-white; Puresteel Paladin specifically rewards equipment-matters, currently not a theme in any Block decks outside of that one Goblin Gaveleer deck I saw once.
One of Inkmoth Nexus's greatest uses is its interaction with planeswalkers, which are some of the most powerful spells in the format. It can defend them and attack them. What with the lack of haste creatures in the format, Inkmoth will be your only real way to touch them, in some decks.
If your deck can run Inkmoth Nexus, it's a good idea to figure out some way to get value from them, beyond having a creature for the combat phase. If your deck can't run Inkmoth Nexus, that's fine, as you should be running more powerful spells to compensate. Utility lands are great but only go so far.
The Other Lands
As @LuisScottVargas pointed out on Twitter, "the mana in block constructed is just horrible." Tru dat, LSV, tru dat.
However, there is nothing wrong with that. It just changes the way we build decks. The risk of going three-color is much greater here than in other recent blocks. Zendikar had two cycles of duals, while Scars only has one. And all the best mana-fixing is artifact-based, which tends to be unreliable when there's a war against artifacts going on with lots of ways to kill them for value.
Some people shrug their shoulders and cast their Spheres of the Suns regardless, but if you overly rely on those Spheres, you'll get blown out by the decks running a million ways to kill artifacts. Of course, it'll all depend on how inbred the format gets before the Pro Tour (this is why we're discussing Block at all, right?).
With this, we can assume that decks will largely be monocolor or two-color. With some notable exceptions.
Alternative Mana-Fixing
Viridian Emissary is one way to get those lands onto the battlefield, given that they die for the cause. How do we kill these guys? That's another matter. Throwing these out there: Vivisection, Birthing Pod, Mortarpod, Artillerize. Another way is via fallout damage from Black Sun's Zenith, Slagstorm, Whipflare, or Ratchet Bomb, assuming you want to cast these spells regardless.
However, this is probably the wrong way to think about this card. It's not a ramp spell, and working to make it ramp or fix is putting in too much work on your part. It's a creature first, which simply punishes your opponent for dealing with it. The question is how badly does it punish them?
The rest of your deck needs to be able to use this bonus mana for maximum damage.
It's very similar to using Path to Exile against a Jund deck—say, on their Putrid Leech. You want to save yourself the damage, but you also don't want to help them fix their mana or ramp them into Broodmate Dragon.
Find the Broodmate Dragons of the format, and you can use Viridian Emissary to your full advantage.
One deck that runs him currently as a four-of is a G/W Midrange deck that can use the Emissary no matter whether it lives or dies. See, if he lives, he can a) wear a sword b) get pumped by Hero of Bladehold c) hold back such pests as Neurok Commando and Leonin Relic-Warder. If he dies, he just ramps you into things like Elspeth Tirel and Sunblast Angel. It's a "pick your poison" situation—although… the deck kills with regular damage. :P
The trick is just to get as much value from both "modes" of this creature as possible.
Another notable deck that uses four Viridian Emissaries is RUG. At the top end, it has Consecrated Sphinx, Volition Reins, and Red Sun's Zenith. It's not super aggressive and will most likely just chump with an Emissary, but doing so helps it reach its more powerful spells to overwhelm aggressive adversaries.
Another new card from NPH has piqued my interest: Mycosynth Wellspring. It's an Ichor Wellspring that specifically tutors for basic lands. I happen to like it a lot, but it's still kind of fringe, sort of like Pilgrim's Eye. But hey, Pilgrim's Eye saw play, so this probably has its place!
The one thing I see doing with it is using it with Tezzeret, Agent of Bolas. Unlike with Sphere, the opponent doesn't have immediate and unhindered incentive to kill it, since it feels like a waste of a removal spell. This leaves it hanging around so that Tezzeret can boost it later—although at that point, they probably will use the removal if they have it.
Alternatively, you can use it with Venser, the Sojourner (the least loved planeswalker in all of Block).
I've been writing and thinking much more about Block than the little you see here, but I think I'm going to cut it here for now. The lands in the format are always an important place to start, always. I didn't even mention Horizon Spellbomb, which also sees plenty of play. I didn't mention Contested War Zone or Phyrexia's Core, the alternate utility lands, certainly much more niche than Inkmoth Nexus. But I think this basic introduction should give you some idea of what Block entails and what kinds of decks will be viable.
I'm not much of a brewer to be honest; however, I am testing and thinking about Block a lot lately, so feel free to drop me a line if you want to chat up some Block.
I only ask that you understand that information is not sacred with me and may be shared amongst others, unless you specifically ask that it does not be shared. I'm not testing for a specific group or testing team. I'm doing this for myself because I want to break the format—or at least attempt to solve the puzzle. I also just love talking and thinking about Magic! Even though I will not be attending the Pro Tour myself, I welcome you to ask me for ideas and throw ideas off of me. I'm collecting decklists, testing them, and trying to piece together the important cards and strategies of Block. The picture is not yet clear, but I'm hoping that by the time Nagoya rolls around, it will be.
