Most played cards in U/B/w Control:

5 Decks
Damnation
16 copies - 3.2 average
Snow-Covered Plains
16 copies - 3.2 average
Cryptic Command
12 copies - 2.4 average
Tolaria West
12 copies - 2.4 average
Prismatic Lens
12 copies - 2.4 average
Urborg, Tomb of Yawgmoth
11 copies - 2.2 average
River of Tears
11 copies - 2.2 average
Careful Consideration
11 copies - 2.2 average
Snow-Covered Island
10 copies - 2 average
Mystical Teachings
10 copies - 2 average
Extirpate
9 copies - 1.8 average
Shriekmaw
9 copies - 1.8 average
Underground River
8 copies - 1.6 average
Coalition Relic
7 copies - 1.4 average
Slaughter Pact
6 copies - 1.2 average
Dodecapod
6 copies - 1.2 average
Detritivore
5 copies - 1 average
Tendrils of Corruption
5 copies - 1 average
Bottle Gnomes
5 copies - 1 average
Terramorphic Expanse
5 copies - 1 average