One of the most prodigious combos in Legacy is that of Painter's Servant and Grindstone. This is a combination of cards that can be assembled as early as the second or third turn of the game, thanks to acceleration like Ancient Tomb, Mox Opal, and Lion's Eye Diamond. Painter's Servant changing the colors of cards has led it to be included in decks with maindeck Pyroblasts and Red Elemental Blasts, but today's deck is more focused on artifact synergies:
Mono-Blue Painter - Legacy | The_Atog_Lord, 5-0 Legacy League
- Sorceries (1)
- 1 Transmute Artifact
- Enchantments (2)
- 2 Search for Azcanta
- Artifacts (14)
- 1 Engineered Explosives
- 1 Ensnaring Bridge
- 1 Ratchet Bomb
- 2 Grindstone
- 2 Sorcerous Spyglass
- 3 Chrome Mox
- 4 Chalice of the Void
This deck is very much like the turbo Blood Moon decks. You have Chalice of the Void to try to lock your opponent out of the game or Sorcerous Spyglass to snipe key permanents like fetchlands or Deathrite Shaman.
Alternatively, you can play a more midrangey gameplan. You have Force of Will to prevent your opponent from getting too out of control, as well as Thirst for Knowledge and Whir of Invention to provide some card selection and let you assemble combo pieces or find powerful singletons that swing matchups, like Spellskite and Ensnaring Bridge.
In the end, this deck is trying to assemble the Painter's Servant and Grindstone combo. You can combo as early as turn two off of just Ancient Tomb and City of Traitors, and you have the likes of Thirst for Knowledge, Trinket Mage, and Whir of Invention to help back it up.
If people are relying too much on the likes of Blood Moon and Back to Basics for free wins, or expecting grindy Blue mirrors that are fundamentally about cards like Ancestral Vision and Jace, the Mind Sculptor, then maybe your metagame is in a place where you can steal games with this style of fast combo deck.