Most played cards in U/B Control:

1 Decks
Mana Leak
4 copies - 4 average
Polluted Delta
4 copies - 4 average
Spell Snare
4 copies - 4 average
Circle of Protection: Red
4 copies - 4 average
Hinder
4 copies - 4 average
Smother
4 copies - 4 average
Ancestral Vision
4 copies - 4 average
Damnation
4 copies - 4 average
Cryptic Command
4 copies - 4 average
Engineered Explosives
4 copies - 4 average
Flooded Strand
4 copies - 4 average
Tombstalker
3 copies - 3 average
Watery Grave
3 copies - 3 average
Cranial Extraction
3 copies - 3 average
Vendilion Clique
3 copies - 3 average
Vedalken Shackles
3 copies - 3 average
Glen Elendra Archmage
2 copies - 2 average
Urza's Factory
2 copies - 2 average
Echoing Truth
1 copies - 1 average
Sunken Ruins
1 copies - 1 average