Most played cards in Solar Flare:

2 Decks
Gifts Ungiven
8 copies - 4 average
Path to Exile
8 copies - 4 average
Snow-Covered Island
6 copies - 3 average
Urza's Power Plant
4 copies - 2 average
Urza's Mine
4 copies - 2 average
Hallowed Fountain
4 copies - 2 average
Urza's Tower
4 copies - 2 average
Ice-Fang Coatl
4 copies - 2 average
Champion of Wits
4 copies - 2 average
Arcum's Astrolabe
4 copies - 2 average
Flooded Strand
4 copies - 2 average
Celestial Colonnade
4 copies - 2 average
Azorius Signet
4 copies - 2 average
Misty Rainforest
4 copies - 2 average
Teferi, Time Raveler
4 copies - 2 average
Surgical Extraction
3 copies - 1.5 average
Ashiok, Dream Render
3 copies - 1.5 average
Veil of Summer
3 copies - 1.5 average
Timely Reinforcements
3 copies - 1.5 average
Celestial Purge
3 copies - 1.5 average