The land base is the most extensive strategy. To have a consistent early game, it is important to have the right colours of mana available. For this reason the deck has a number of fetch lands, and lands that can produce one of the two required colours. While selecting utility and combat lands, it was important that they help negate Boros weaknesses and provide support to the Voltron strategy.
COLOUR LANDS
Battlefield Forge
City of Brass
Command Tower
Mana Confluence
Plateau
Rugged Prairie
Sacred Foundry
3x Snow-Covered Mountain
5x Snow-Covered Plains
Spectator Seating
Sunbaked Canyon
The nonbasic lands in this deck are the best lands that provide the deck’s colours without entering the battlefield tapped. Plateau and Sacred Foundry are also targets for fetch lands with their basic land types.
Snow-Covered basic lands were selected for this deck primarily because of Search for Glory, a tutor spell that can search for a snow permanent, providing the flexibility of tutoring a basic land if needed.
FETCH LANDS
Arid Mesa
Marsh Flats
Scalding Tarn
Prismatic Vista
Fetch lands are simply the best way of ensuring to have the right colours available at most times. There could be more in the deck but I found this number to be a good amount.
UTILITY LANDS
Ancient Tomb
Cavern of Souls
Command Beacon
Field of Ruin
High Market
Homeward Path
War Room
Urza's Saga
Utility lands vary from providing a mana boost, to mitigating Boros weaknesses or supporting the strategy.
Ancient Tomb and Urza’s Saga are excellent in the first three turns. The Saga has added benefits of being an enchantment that can be tutored for, and its third ability has multiple targets in the deck; from mana rocks to Equipments.
Cavern of Souls is best against control decks, or any decks that run counterspells. Successfully casting the commander is quite important to the strategy.
Command Beacon becomes useful in the late game when the commander tax is high as it can potentially save a lot of mana. It is not uncommon for the commander tax to be as high as 10 mana.
Field of Ruin is included to have at least one answer to lands that might need to be destroyed. Of all the lands that can destroy other lands, this one was selected because it effectively replaces itself.
High Market is a sacrifice outlet on a land, which synergises well with the sacrifice and recursion tactic. The sacrifice outlets are spread among different card types to increase the likelihood of drawing one or being able to tutor for one.
Homeward Path is another protection against control, or any effect that places the commander under an opponent’s control. Since the commander is the key to the Voltron strategy, it is important it remains under its owner’s control.
War Room is one of few lands that can draw cards. Three mana and two life is not the best value for one card, but it can be helpful to have that option available.
COMBAT LANDS
Cathedral of War
Hanweir Battlements
Rogue's Passage
Shinka, the Bloodsoaked Keep
Slayers' Stronghold
Cathedral of War is the only land in the deck that unconditionally enters the battlefield tapped, but offers good value with its passive exalted ability which boosts Avacyn’s power and toughness when the commander attacks alone, which is the majority of time.
Hanweir Battlements is included in the deck for its ability to give haste, the meld ability never happens because the deck doesn’t include the Hanweir Garrison card. The ability to give haste is most useful in the late game when it is preferable to attack on the same turn as being re-cast.
The easiest way for Avacyn to do combat damage is for the commander to be unblockable, which makes Rogue's Passage a natural fit in the deck.
Shinka, the Bloodsoaked Keep’s ability to provide a legendary creature with first strike is rarely used but it can be useful in certain situations, and the legendary type allows the Keep to be tutored for.
Slayers' Stronghold has a great value for mana ability, providing haste, vigilance and power boost for only two mana. The Stronghold is the most valuable when Avacyn transforms into the Purifier because she loses vigilance.