Most played cards in Drain Tendrils:

2 Decks
Accumulated Knowledge
8 copies - 4 average
Force of Will
8 copies - 4 average
Duress
8 copies - 4 average
Burning Wish
8 copies - 4 average
Brainstorm
8 copies - 4 average
Mana Drain
8 copies - 4 average
Polluted Delta
6 copies - 3 average
Flooded Strand
6 copies - 3 average
Intuition
6 copies - 3 average
Underground Sea
5 copies - 2.5 average
Rack and Ruin
4 copies - 2 average
Volcanic Island
4 copies - 2 average
Tendrils of Agony
2 copies - 1 average
Rebuild
2 copies - 1 average
Tolarian Academy
2 copies - 1 average
Time Walk
2 copies - 1 average
Sol Ring
2 copies - 1 average
Coffin Purge
2 copies - 1 average
Meltdown
2 copies - 1 average
Lava Dart
2 copies - 1 average