aka: Oath Control
Oath of Druids has an effect too powerful even for Legacy, and the Oath deck is uniquely vintage, with no real analog in other formats.
By playing a deck with only a handful of extremely strong creatures, Oath of Druids combined with Forbidden Orchard can put cards into play that have no business costing two mana. Against aggressive decks that need to get creatures into play, Oath of Druids can single-handedly decide the game.
Oath decks allow for tons of personalization, and throughout vintage history have ranged from pure combo, to fish-like tempo, to their most common iteration today, a controlling list that plays defensively with a big finish.
Why Play Oath
Mox. Orchard. Oath.
Got a Force of Will? So do I.
One of the most feared openings in vintage, and you get to run four. Oath is a deadly, fast, compact combo that puts your opponent on the defensive from the first turn.
Vintage these days is more creature-centric than ever, which means even just the threat of an Oath of Druids in your deck can impact the way your opponent has to play the game.
Oath lists have tons of variety between them, and small changes in creature makeup can have a big impact on how games play out, making it a great deck for tinkerers.
Why WOULDN'T you play Oath?
As much as Oath can do with a few good cards, sometimes it has real trouble drawing a few bad ones. Oath decks run a lot of cards that can occasionally make you lose to yourself. A hand full of Forbidden Orchards might leave you dead before you draw an Oath of Druids. A hand full of seven-cost creatures might not do anything at all. Even a great Orchard/Oath opening could leave you stranded with no library if all of your creatures have to be on the bottom of your deck.
Experienced Oath players know how to minimize these problems, but variance will still bite you now and again.
The unique requirements of the card Oath of Druids mean you can't run any cheap utility creatures if you don't want to Oath them up by accident, and while Forbidden Orchard is one of the deck's strengths, it does put some tension on the way you build your manabase.
Oath decks will often run cantrips and draw spells, similar to most blue control decks, to smooth out draws. Because of the high variance in cards an Oath deck wants to draw or avoid, filtering cards, like Dig Through Time and Brainstorm are even better than they usually are, and raw draw spells slightly worse.
Jace, the Mind Sculptor is particularly notable as a hand-fixer, while acting as a secondary win-condition that doesn't get in the way of Oath activations.
Oath usually runs somewhere between 2 and 4 extremely threatening creatures, often a mix designed to handle different situations. A creature's raw power, their resistance to different answers, and their castability are all important considerations.
Some Oath players will run even more specialized creatures in their sideboard, the full list of options would be too large to list here.
Disruption and Defense
Because an Oath deck actively wants creatures in play, dedicated creature removal is less critical, though a postboard answer to a pesky Containment Priest is useful.
Grafdigger's Cage is by far the most common anti-Oath sideboard card, so any good Oath deck is prepared for it. Abrupt Decay is versatile removal for the manabases that support it, and Ancient Grudge is a nice answer which happens to be very useful against Workshop-style decks as well.
Salvagers Oath, Kelly Oath: bant-colored with the Auriok Salvagers/Black Lotus combo, heavy on control elements
Griselbrand Oath, Fenton Oath: Aggressive Oath deck featuring Griselrbands, Show and Tells and the Time Vault/Voltaic Key combo
Punishing Oath: runs the Punishing Fire/Grove of the Burnwillows combo as board control and a secondary win condtion
Golden Gun Oath: runs Dragon's Breath to attack with a lethal Blightsteel Colossus or Emrakul, the Aeons Torn the turn Oath is activated
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