Most played cards in Boros:

1 Decks
Cleansing Wildfire
4 copies - 4 average
Boom // Bust
4 copies - 4 average
Lightning Bolt
4 copies - 4 average
Cascading Cataracts
4 copies - 4 average
Relic of Progenitus
4 copies - 4 average
Nahiri, the Harbinger
4 copies - 4 average
Sacred Foundry
4 copies - 4 average
Pillage
4 copies - 4 average
Flagstones of Trokair
4 copies - 4 average
Defense Grid
3 copies - 3 average
Boil
2 copies - 2 average
Anger of the Gods
2 copies - 2 average
Mazemind Tome
2 copies - 2 average
Gideon of the Trials
2 copies - 2 average
Darksteel Citadel
2 copies - 2 average
Wrath of God
2 copies - 2 average
Oust
2 copies - 2 average
Celestial Purge
2 copies - 2 average
Temple of Triumph
2 copies - 2 average
Timely Reinforcements
2 copies - 2 average