Most played cards in Ad Nauseam-Conflagrate:

3 Decks
Mystical Teachings
12 copies - 4 average
Pact of Negation
12 copies - 4 average
Ponder
12 copies - 4 average
Thoughtseize
12 copies - 4 average
Lotus Bloom
12 copies - 4 average
Vivid Crag
12 copies - 4 average
Angel's Grace
12 copies - 4 average
Ad Nauseam
12 copies - 4 average
Coalition Relic
12 copies - 4 average
Grove of the Burnwillows
12 copies - 4 average
Simian Spirit Guide
11 copies - 3.67 average
Punishing Fire
11 copies - 3.67 average
Vivid Creek
11 copies - 3.67 average
Reflecting Pool
11 copies - 3.67 average
Preordain
8 copies - 2.67 average
Spell Pierce
6 copies - 2 average
Underground River
6 copies - 2 average
Vivid Marsh
5 copies - 1.67 average
Slaughter Pact
4 copies - 1.33 average
Swerve
3 copies - 1 average