The marquee strategy in Legacy at the moment appears to be various decks using Delver of Secrets. These decks lean on a high volume of cantrips and efficient threats backed by free counterspells to win games where neither player has many resources to work with. Consequently, many players are looking for ways to either force through cards that can trade for multiple resources or lock pieces that prevent opponents from leveraging mana-light strategies. An extreme example is this Black lockdown deck featuring Smokestack by Alexander Cantrell:

Mono-Black Smokestack - Legacy | Alexander Cantrell, Legacy Champs

• Creatures (8)
• 4 Ophiomancer
• 4 Braids, Cabal Minion

• Sorceries (3)
• 3 Toxic Deluge

• Artifacts (25)
• 2 Crucible of Worlds
• 2 Sorcerous Spyglass
• 2 Trading Post
• 3 Ensnaring Bridge
• 4 Chalice of the Void
• 4 Mox Diamond
• 4 Smokestack
• 4 Trinisphere

• Lands (25)
• 5 Swamp
• 1 Dunes of the Dead
• 1 Inventors' Fair
• 1 Peat Bog
• 1 Urborg, Tomb of Yawgmoth
• 4 Ancient Tomb
• 4 Cavern of Souls
• 4 City of Traitors
• 4 Wasteland

• Sideboard (15)
• 1 Bottled Cloister
• 2 Collective Brutality
• 4 Helm of Obedience
• 4 Leyline of the Void
• 2 Perish
• 1 Phyrexian Revoker
• 1 Virtue's Ruin

Buy This Deck

The core premise of this deck is that, at some point, you’re going to resolve a Smokestack or Braids, Cabal Minion. At that point, opponents who are heavy on spells and light on permanents are going to struggle to keep enough lands in play to put up much of a fight. It’s important to remember that you can stack your Smokestack triggers such that you sacrifice first and then have the option to add a soot counter, that way your opponent will always be sacrificing one more permanent than you are.

One problem with this style of deck is that it is very much dependent on denying your opponent permanents, with no way of efficiently interacting with the hand. This means that you’re vulnerable to combo decks that don’t need an untap step, like Storm and some variants of Show and Tell. In those matchups, you have to rely heavily on Chalice of the Void and Trinisphere while bringing in your own combo to race: Leyline of the Void and Helm of Obedience, which can mill your opponent out in one go.

If you’re looking for an off-the-wall way to punish Blue decks that are either lean on mana or are dependent on developing a lot mana, this seems like a very reasonable way to do it. Certainly, you’re not necessarily going to have a great time against cards like Daze, but Chalice of the Void and Trinisphere have proven themselves to be a force in the format, and the greedier people are getting, the better Smokestack is going to be.