Most played cards in Death and Taxes:

3 Decks
Ghost Quarter
12 copies - 4 average
Path to Exile
12 copies - 4 average
Thalia, Guardian of Thraben
12 copies - 4 average
Aether Vial
12 copies - 4 average
Flickerwisp
12 copies - 4 average
Leonin Arbiter
12 copies - 4 average
Tectonic Edge
8 copies - 2.67 average
Thraben Inspector
8 copies - 2.67 average
Relic of Progenitus
8 copies - 2.67 average
Horizon Canopy
8 copies - 2.67 average
Blade Splicer
8 copies - 2.67 average
Restoration Angel
8 copies - 2.67 average
Stony Silence
7 copies - 2.33 average
Mirran Crusader
6 copies - 2 average
Tidehollow Sculler
4 copies - 1.33 average
Burrenton Forge-Tender
4 copies - 1.33 average
Grafdigger's Cage
4 copies - 1.33 average
Thought-Knot Seer
4 copies - 1.33 average
Caves of Koilos
4 copies - 1.33 average
Dusk // Dawn
4 copies - 1.33 average