The usual Legacy combo decks (ANT, TES, Thopter, Imperial Painter) rely upon *re*active strategies to protect the combo (usually using counterspells), and attempt to go off as quickly as possible to prevent stabilization by the opponent.
This deck is based upon an alternative plan - that of *pro*actively disrupting the opponent and controlling the board and opponent's hand until such time that the combo is assembled and goes off (usually 1-2 turns slower than the "usual" combo speed of turns 2-3). As Legacy combo has reached near-peak efficiency (2 card combo requiring 1 & 2 colourless mana respectively, both tutorable with the same W casting cost instant which can also tutor other silver bullet hate cards), this leaves great amounts of deck space to dedicated hate, control and disruption, which has become more and more general-purpose and mana-efficient with each passing set. The time is ripe for this sort of control-combo deck.
The fundamental reason for this is that disruption only slows the opponent down - pure disruption is a losing strategy as the opponent must be expected to make some sort of wincon stick in the end. However, the nature of combo is that it can "go off" and win instantaneously, which is perfect when combined with a good disruption and board control suite to ensure that the opponent cannot interfere effectively. Rather than racing other decks (which is boring, and not necessarily effective as Legacy anti-combo hate becomes more and more effective and efficient), why not *address* the hate head-on?
Unfortunately, many hate cards trade 1-for-1. Hence the stress about card advantage in general. However, the use of a 2-card combo win condition totally throws that equation out of the window - you are HAPPY to trade your hate 1-for-1 for ALL their threats, since at some point, you'll get 2 cards and win outright, and until then, EVERYTHING ELSE is dedicated to making sure the opponent DOES NOT WIN.
The inclusion of Extirpate and Surgical Extraction is deliberate. As Legacy decks become more and more streamlined, more and more decks depend on "key" cards - such as just 2x4 beaters in the typical Aggro-Control or Aggro-Disruption deck. Once half, or even all of these are stripped by one or two well-placed spells, those decks have auto-lost. Dredge has little chance against such hate as well (particularly when combined with all the other disruption in this deck). Even against multiply redundant decks like the Tribes - Elves, Goblins, Merfolk, these can still strip out important cards like Lords, Piledrivers, Natural Order, Green Sun's Zenith, Force of Will, AEther Vial, etc.
Main wincon: Grindstone+Painter's Servant
Alternate wincon / Recurring blocker: Mishra's Factory (Crucible)
Hand Disruption: Inquisition, Smallpox, Hymn, Thoughtseize
Land Disruption: Wasteland (Crucible), Smallpox, Sinkhole, Vindicate
Combo/Key Card Disruption: Extirpate, Surgical Extraction - Grindstone without Painter's Servant can still fill GY for Extirpate and Surgical Extraction!, Vindicate, Ethersworn Canonist (SB), Phyrexian Revoker (SB), COP (SB)
Creature Removal: Cabal Pit (Crucible), Smallpox, Swords, Vindicate, Innocent Blood (SB), Ratchet Bomb (SB)
GY Hate: Bojuka Bog, Extirpate, Surgical Extraction
Still considering other SB cards. SB is work in progress. Circle of Protections picked due to colourless mana requirements to activate - the CoPs are meant as speedbumps against fast aggro which sneaks creatures onto the board despite disruption, and keeps them there through all the removal this deck packs. CoP:Red = autowin vs Burn (bonus!!) and makes Gobbos think long and hard. CoP:Green really crimps the style of Zoo and Elves if not answered. CoP:Blue screws Merfolk. CoP:Black versus Gate, Eva Green, Black Aggro, etc. Singletons as part of toolbox build with Enlightened Tutor.
Am also considering replacing Mishra's Factory with a singleton Phyrexian Totem as a tutorable alternate wincon. Faster clock, but non-recyclable. Both are mana producers, so that's a moot point. Phyrexian Totem costs 3, but since it's an alternate wincon, that's a minor consideration.
1 major deck weakness, although this is a moderately rare play - 1st turn Chalice@1. Only answer is Vindicate - 3 MD and 1 SB (assuming Chalice is resolved, of course - plenty of ways to strip it out of opponent's hand if you're on the play Turn 1). Thank goodness decks that can race this deck (combo, fast aggro), rarely, if ever, pack Chalice, and almost never 4 copies even if they do.
Was debating Dark Ritual, but decided against it. Firstly no deck space. Secondly, although it allows explosive starts, it's often a dead draw past the first 2 turns. Thirdly, we WANT the opponent to establish a *minor* board presence in the first turn or two - a significant part of this deck's control elements are based upon removing cards that have resolved! (Particularly Smallpox)