Most played cards in Grand Arbiter Augustin IV:

3 Decks
Impulse
3 copies - 1 average
Mana Tithe
3 copies - 1 average
Miscalculation
3 copies - 1 average
Counterspell
3 copies - 1 average
Brainstorm
3 copies - 1 average
Windswept Heath
3 copies - 1 average
True-Name Nemesis
3 copies - 1 average
Balance
3 copies - 1 average
Council's Judgment
3 copies - 1 average
Oust
3 copies - 1 average
Timely Reinforcements
3 copies - 1 average
Jace, the Mind Sculptor
3 copies - 1 average
Search for Azcanta
3 copies - 1 average
Teferi, Hero of Dominaria
3 copies - 1 average
Swords to Plowshares
3 copies - 1 average
Spell Pierce
3 copies - 1 average
Path to Exile
3 copies - 1 average
Ponder
3 copies - 1 average
Preordain
3 copies - 1 average
Temple of Enlightenment
3 copies - 1 average