Generating extra mana in the early game is essential for the strategy of attacking with the commander as soon as possible. With the right mana rocks in the opening hand, Archangel Avacyn can be cast as soon as turn one. In the later game, having access to more mana also helps with re-casting the commander. This extra mana is generated in three ways; by mana rocks, creating treasures and tutoring for lands.
Talisman of Conviction
All the mana rocks were purposefully chosen to be mana value 2 or less so that they can be impactful in the first few turns. Some of the mana rocks help with colour fixing, while others have additional utility beside generating mana.
Dockside Extortionist is often most impactful in the early game to get a boost of mana, and Smothering Tithe provides great value throughout the game. In this deck there is also potential for the Extortionist to trigger more than once by recurring from the graveyard or flickering from and to the battlefield.
Bitterthorn, Nissa's Animus
Dowsing Dagger // Lost Vale
The Boros colours are inherently limited in land ramp. Dowsing Dagger provides a good mana boost when transformed, and Bitterthorn, Nissa's Animus works well to provide an additional land for the next turn as it triggers on attacking, and not dealing combat damage. Both of those can also be tutored early in the game. Weathered Wayfarer is a good early turn creature that helps to ensure no land drops are missed, with the added benefit of tutoring for any land.