Most played cards in Boros:

4 Decks
Sacred Foundry
16 copies - 4 average
Path to Exile
11 copies - 2.75 average
Arid Mesa
9 copies - 2.25 average
Clifftop Retreat
8 copies - 2 average
Rest in Peace
8 copies - 2 average
Flagstones of Trokair
8 copies - 2 average
Lightning Helix
8 copies - 2 average
Anger of the Gods
7 copies - 1.75 average
Stony Silence
5 copies - 1.25 average
Student of Warfare
4 copies - 1 average
Selfless Spirit
4 copies - 1 average
Lightning Bolt
4 copies - 1 average
Gideon of the Trials
4 copies - 1 average
Honor of the Pure
4 copies - 1 average
Spectral Procession
4 copies - 1 average
Temple of Triumph
4 copies - 1 average
Brave the Elements
4 copies - 1 average
Hero of Bladehold
4 copies - 1 average
Nahiri, the Harbinger
4 copies - 1 average
Goblin Guide
4 copies - 1 average