Legacy is a strange format. There are few other formats where decks are so efficient and powerful, and yet do so little. An overwhelming majority of the best decks in Legacy are packed to the brim full of powerful card selection like Brainstorm and Ponder. This makes them great at doing one powerful thing, like resolving Show and Tell to put Griselbrand into play or finding the perfect combination of Invigorates and Infect creatures. However, when decks become too linear, they open themselves up to interesting angles of attack, like this one from PirateKing:

U/B Pox ? Legacy | PirateKing

• Creatures (9)
• 2 Phantasmal Image
• 3 Bloodghast
• 4 Snapcaster Mage

• Planeswalkers (4)
• 2 Jace, the Mind Sculptor
• 2 Liliana of the Veil

• Spells (29)
• 4 Brainstorm
• 4 Extirpate
• 4 Surgical Extraction
• 2 Ponder
• 2 Thoughtseize
• 3 Smallpox
• 4 Cabal Therapy
• 4 Gitaxian Probe
• 2 Crucible of Worlds

• Lands (18)
• 1 Island
• 4 Swamp
• 2 Creeping Tar Pit
• 3 Wasteland
• 4 Polluted Delta
• 4 Underground Sea

• Sideboard (15)
• 2 Flusterstorm
• 4 Force of Will
• 2 Pithing Needle
• 3 Dark Ritual
• 2 Toxic Deluge
• 2 Echoing Truth

Buy This Deck

The deck hinges on the idea that most Legacy decks play a whole mess of cantrips and very few important cards. The game plan is to lead off with hand disruption in the form of Cabal Therapy or Thoughtseize on key cards like Stoneforge Mystic, Show and Tell, or Lion's Eye Diamond. Then you can follow up by exiling all copies of that effect with a Surgical Extraction or Extirpate. Rinse and repeat with Snapcaster Mage functioning as backup copies of both the discard spell and the exiling effect. If you are able to Surgical Extraction or Extirpate the few important cards, you can win the game at your leisure with Bloodghast and Creeping Tar Pit beatdown.

Even against aggressive Delver of Secrets variants, the combination of Smallpox, Wasteland, and Surgical Extractions is shockingly powerful. Very few decks play more than a handful of lands, most of which are non-basics. This means you have the ability to Extract the bulk of your opponent's mana-producing lands early in the game and potentially even cut them off of a color entirely. All of this adds up to your opponents doing an awful lot of nothing while you apply pressure with Bloodghasts and Creeping Tar Pits. Alternatively you can just keep your opponent low on resources and resolve a Planeswalker like Jace, the Mind Sculptor or Liliana of the Veil to take over the game.

When the format shifts toward Death and Taxes and other creature oriented decks, this style of deck is largely ineffective because so many of their cards are basically interchangeable. However, decks heavily reliant on narrow subsets of cards, be they dual lands, combo pieces, or minimal threats to actually win the game, then it may be a good opportunity for this strategy to shine.