A lot of people have published articles about the next great combo. They all run something like this:"Play these cards do this and win. Turn 5! No, 4! 3! It's great! / It wrecks the format! / It shows I'm amazing!" Yadda, yadda, yadda.
It's bullsh... Okay, I can't say that, but it's still stuff you don't want to step in.
These people have no clue. You don't build combo decks to goldfish. You build combo decks to play in tournaments. That means you have to build a deck that can survive an active opponent, not a goldfish.
I have often written about potential combos, and why those combos don't work. I keep harping on three rules for combos.
1) Find the pieces.
2) Don't play bad cards.
3) Three pieces, or fragile pieces, make garbage.
If you are trying to build a combo deck, you need searching power to find the pieces. You need to play cards that don't suck when you don't have the combo - or be absolutely certain you will find the combo. And you need to have a combo that is redundant or reliable enough that it won't be disrupted. The current crop of Netdecks - at least the combo versions - fail these tests.
Let's look at the Block format, since that is the next Constructed PTQ season. No one will play Type Two in the next few months, unless they are playing FNM or side events at gaming conventions. (US Nationals doesn't count - it doesn't allow Fifth Dawn and does allow Skullclamp, so it's history - future history, but history.) Let's take a look at some combo examples that are all over the net. Here's a typical Ironworks combo deck, from Phil Smith on some other site.
4 Myr Enforcer
4 Chromatic Sphere
4 Krark-Clan Ironworks
4 Pentad Prism
4 Serum Visions
4 Thirst for Knowledge
4 Wayfarer's Bauble
4 Welding Jar
4 Great Furnace
4 Seat of the Synod
It has a combo - Krark-Clan Ironworks, sac lots of artifacts and Fireball them to death. It has a fallback plan: beatdown with Myr Enforcer. It has some card drawing, with Serum Visions, Thirst for Knowledge, Chromatic Sphere, and Wayfarer's Bauble. It probably goldfishes well. It would be even better if he included Myr Retrievers.
The problem is that it has absolutely no regard for what an opponent does. For example, take a look at mono-Green beats deck. Yes, they exist. At least two appeared in the top 32 at PT Kobe, and this deck is just Mirrodin / Darksteel - it doesn't even run Tel-Jilad Justice and other new spells.
Matteo Cirigliano: Mono-Green Beats
4 Blinkmoth Nexus
4 Tel-Jilad Chosen
4 Viridian Zealot
4 Viridian Shaman
4 Troll Ascetic
4 Fangren Firstborn
4 Molder Slug
3 Predator's Strike
2 Pulse of the Tangle
A quick note: work and travel have meant that I have time to write, but not a ton of time to playtest. I haven't played this matchup fifty times yet, but from what I have played, I can say that having twenty-three maindeck means of destroying artifacts makes it pretty hard to rely on getting the combo out and going off. If the metagame changes a bit, I would also look at removing the Molder Slugs and adding some Isochron Scepters and Tel-Jilad Justice. The Scepter is pretty good with Oxidize, Predator's Strike, and TJ Justice. But I digress - the point is that this tried and proven deck smashes the combo.
I would also note that Smith's combo deck has absolutely no method of handling Damping Matrix, if it hits play on turn 2 or 3. No way. Scoop 'em up.
Other versions of the Ironworks combo run Myr Incubator. These decks drop artifacts, play the Ironworks, sac three artifacts to play the Incubator, and another three to activate it. Then they remove twenty to thirty artifacts from their deck to create Myr, sacrifice those to generate a lot of mana, play Goblin Cannon, sacrifice more artifacts to power it and then kill you. At least, that's the goldfish scenario.
Here's how it plays out in the real world. The combo player sacrifices most of his artifacts for mana and activates the Incubator. The opponent Shatters or Oxidizes the Ironworks in response. How many Myr does the combo player make, at that point? Does he remove most of his deck for thirty Myr, not knowing if his opponent has an Echoing Ruin / Truth / Decay in hand? Does he just get a couple Myr? In any case, he now has no non-Myr permanents, very little hand and very little chance of winning the game.
Here's another scenario - let's say that I am playing a Blue Affinity deck against the combo player. I have a few counterspells, say four Condescend, plus some Vexes / Override / whatever, and some Annuls in the sideboard. How many spells do I have to counter, exactly, to beat Phil Smith's decklist? I think the answer is four Fireballs, although I might also be willing to waste a Condescend or Override on the Ironworks, especially if the deck had Myr Retrievers (which go infinite, so Mana Leak effects are useless.) Of course, I will be running Damping Matrix in my deck, so I only need the counterspells early, before he has done much development and before I drop the Matrix. After that, the counters serve to protect the Damping Matrix while Broodstar (or, more likely Qumulox) kills him. (Open questions: Can control Affinity handle the mono-Red control decks? Maybe, maybe not - depends on the builds. Can the mono-Red control decks handle combo - also an open question, and if they cannot, then they are gone. The format may change a lot.)
I think Condescend redefines the format. Just like last year, where the Onslaught block PT featured a lot of big creatures (remember the Kilnmouth Dragon decks?) that got everyone excited. Then the final block arrived, with just enough additional counters and removal (e.g. Wing Shards) to make the large creature decks unplayable. I predict the same fate for TwelvePost and this format - the available pool of counters just got big enough that the always slightly erratic Tooth and Nail decks are now dead in block. The decks are still powerful, but a control deck will shut them down - and if the deck has a seriously bad matchup, those loses, in addition to the matches you lose to bad draws and stalls, the deck becomes too unreliable for a PTQ.
I think the best build of Ironworks would begin with the Ironworks, Myr Retriever, and the Goblin Cannon kill, plus Thirst for Knowledge and so forth, but also include counters and protection, and probably Echoing Truth. It is depressing to scoop to Damping Matrix. It might even run Vex. Vex is a horrible counter in most cases - but allowing an opponent to draw another card when your combo is about to win you the game is fine. There is no Force of Will or Misdirection in Mirrodin Block, so that card should not be able to disrupt you. (If I missed something, tell me in the forums.)
Everyone has looked at Ironworks as the heart of a combo deck, but there are some other options that people might try. I have started toying with the Bringer of the White Dawn / Mindslaver combo. That is a very solid lock. The trick is getting that going - but with Chrome Mox and Pentad Prism, the Bringer could hit the table as early as turn 3. You would also need to get the Mindslaver in the graveyard, so add a turn to cast Thirst for Knowledge - but you can pretty reliably get the Mindslaver lock going turn 4 or 5.
The core of the deck is obvious - 4 Mindslavers, 4 White Bringers, 4 Thirst for Knowledge. Beyond that, the deck will depend on the metagame. Thought Courier - the new Merfolk Looter - would be an automatic inclusion in a combo deck that looks to put stuff in the graveyard, but not if the metagame is running lots of Electrostatic Bolts and Pyrite Spellbombs. The mana is also iffy: Pentad Prism or Channel the Suns are better for fast starts, while Talismans, Solemn Simulacrum or even Sylvok Explorer might be better against certain decks. It would be quite easy to run some counterspells in the deck, or something like Echoing Truth (which is also a great answer to Myr Incubator.) The deck could also run Damping Matrix sideboard (although Mindslaver and Damping Matrix are not a combo, you can always beat down with the Bringers. They are 5/5 tramplers, after all.)
If the deck plays for speed, it would run Chrome Moxen, Pentad Prism and so forth. That sort of build would have a faster lock, but it would be more prone to stalling (for example, you can use Pentad Prism once - after that it is dead. A Talisman is slower, but can be used more than once.) The alternative build would play a more defensive game, with cards like Thought Courier digging slowly, while the main mana is used for counters, control and end of turn Thirsts. The exact builds, and the mix of counters, depends on the metagame. As some other writers have noted, you develop the control decks last, after the decks they have to control are fleshed out.
The Mindslaver / White Bringer deck does meet the basic rules of combos. It has search cards and means of finding the pieces. It has counters for protection and disruption. The combo pieces, Mindslaver and Bringer of the White Dawn, have utility even without the combo in place. Only more playtesting will tell if the deck works well enough to find a place, but it looks promising. More promising, in my opinion, than the Ironworks decks built to date.
Note that this deck also works, in theory at least, in Type Two. Birds of Paradise and Mana Leak fit in quite nicely. I'm not looking at the future Type Two right now, I like the idea.
My previous discussion of the Ironworks decks looked at the effect of counters and artifact kill. However, the format also has some discard that could be playable. Fill with Fright is not amazing, but it has scry. Usually that scry will serve to hide any other copies of the card on the bottom of the players library, but the card could be used to strip components out of the hands of combo players getting a slow start. That slow start could be created by Shattered Dreams. Again, this card is certainly not Duress, but it is a solid sideboard card for any heavy Black deck.
The Ironworks combo decks would have a hard time recovering from having a critical part stripped away on turn one (not an impossible time, if decks run Myr Retrievers, but it could still hurt.)
Now I'm not saying that a Black deck is definitely playable, but I don't think it can be dismissed, either. We have grown accustomed to a lack of targeted discard, and we will have to rethink that in designing combo decks. (Note that the Bringer / Mindslaver deck is unaffected by Shattered Dreams - the only artifact to target, Mindslaver, is something we already want in the graveyard.)
A quick recap: yes, people are building decks that can goldfish on turns 2 through 4. Yes, that means that some slow, existing decks may have problems. However, those fast goldfishing combo decks do not tolerate hate, at least not in the form of artifact destruction, counters, discard and Damping Matrix. That makes a difference. People need to start building combo decks for tournament play, not goldfishing.