Most played cards in Death and Taxes:

5 Decks
Containment Priest
19 copies - 3.8 average
Archon of Emeria
19 copies - 3.8 average
Thalia, Guardian of Thraben
19 copies - 3.8 average
Leonin Arbiter
16 copies - 3.2 average
Spirit of the Labyrinth
12 copies - 2.4 average
Ghost Quarter
11 copies - 2.2 average
Cavern of Souls
11 copies - 2.2 average
Path to Exile
9 copies - 1.8 average
Thought-Knot Seer
8 copies - 1.6 average
Ancient Tomb
8 copies - 1.6 average
Luminarch Aspirant
8 copies - 1.6 average
Stony Silence
8 copies - 1.6 average
Simian Spirit Guide
8 copies - 1.6 average
Leonin Relic-Warder
8 copies - 1.6 average
Rest in Peace
8 copies - 1.6 average
Deafening Silence
8 copies - 1.6 average
Palace Jailer
8 copies - 1.6 average
Wasteland
8 copies - 1.6 average
Swords to Plowshares
7 copies - 1.4 average
Glowrider
6 copies - 1.2 average