UPDATED MARCH/2022
The Legacy Stax deck is rumored to receive its name either from the card Smokestack or from the acronym "$T4KS" ("the $4k solution" to the meta it originated in - and considered to be a high price for any deck at the time).
This strategy is present both in Legacy as is in Vintage. And in both formats, it functions similarly: use artifacts to impede the opponent's game-plan.
It falls into the category of Prison decks.
The Smokestack trick
While at first Smokestack seems to be a fair and symmetric card, there is a trick to it that broke the symmetry and gave the Stax player a big advantage.
The trick consists of taking advantage from the order the triggers will resolve in the Stax's player own turn.
By choosing to resolve the sacrifice trigger first and adding a counter second, the Stax player can keep the opponent in constantly in disadvantage and, when it is time, sacrifice Smokestack to its own ability.
It may be a simple trick, but notice how Smokestack is worded. The card gives the impression the triggers are to be resolved in the sequence they are displayed and less experienced players may "roll with it" and resolve it in the "wrong order" by default - and this misleading wording may even have been intentional by design. But in reality both abilities trigger at the same time and the owner chooses which will resolve first and there lies the key to the trick.
This is a sequence of events that would ensue assuming the player keeps adding soot counters - it is a may ability:
- Player's turn: cast Smokestack, 0 soot counters
- Opponent's turn: sacrifices 0 permanents
- Players turn: sacrifices 0 permanents, +1 soot counter= (1 soot counter)
- Opponent's turn: sacrifices 1 permanent
- Players's turn: sacrifices 1 permanent, +1 soot counter= (2 soot counters)
- Opponent's turn: sacrifices 2 permanents
- Player's turn: sacrifices 2 permanents, +1 soot counter (3 soot counters)
- Opponent's turn: sacrifices 3 permanents
By simply choosing the right order of the triggers, the opponent is always suffering more from the Smokestack effect than the Stax player.
Another way to keep the player at advantage and the opponent at disadvantage is to not add more soot counters (mantaining a low number of soot counters) and keeping recursing a land with Crucible of Worlds, Drownyard Temple or even Crucible of Worlds + God's Eye, Gate to the Reikai to progress the board every turn by generating more spirit tokens.
Early Decklists
The deck used cards such as Trinisphere, Smokestack, Tangle Wire, Chalice of the Void, Lodestone Golem and Powder Keg to either prevent the opponent from progressing in the game.
It then proceeded to kill the opponent with Mishra's Factory and Mutavault.
Mana basis (23)
Prison and board control (25)
Sideboard (15)
Contemporary Decklists
As of late, the deck Stax evolved into 2 different artifact-based control decks.
One is still called Stax for its proximity with the original Stax deck, while the other is often referred to as Mystic Forge, Mystic Forge Stax or Stax Forge.
The advent of Urza's Saga, Retrofitter Foundry, Mystic Forge and Karn, the Great Creator greatly benefitted the deck.
Stax
Mystic Forge
Other spells (38)
4 Mox Opal
Sideboard (15)
Notes on Stax
Stax is an overall very expensive deck to play.
It is commonly classified as a "classic deck" by Legacy veterans.
Stax is also considered not to be a beginner's deck. It is composed of some tricky plays and requires extensive knowledge of both the meta it is inserted into as well as the very own deck the Stax player is playing.
Due to its Reserved List dependency it is unlikely to see a decklist welcoming for new budget-limited players.