Most played cards in Spirits:

8 Decks
Rattlechains
24 copies - 3 average
Drogskol Captain
24 copies - 3 average
Mausoleum Wanderer
24 copies - 3 average
Spell Queller
24 copies - 3 average
Selfless Spirit
23 copies - 2.88 average
Path to Exile
22 copies - 2.75 average
Windswept Heath
22 copies - 2.75 average
Flooded Strand
22 copies - 2.75 average
Collected Company
20 copies - 2.5 average
Geist of Saint Traft
17 copies - 2.13 average
Noble Hierarch
17 copies - 2.13 average
Blessed Alliance
12 copies - 1.5 average
Botanical Sanctum
11 copies - 1.38 average
Rest in Peace
11 copies - 1.38 average
Hallowed Fountain
9 copies - 1.13 average
Breeding Pool
9 copies - 1.13 average
Misty Rainforest
9 copies - 1.13 average
Phantasmal Image
8 copies - 1 average
Stony Silence
8 copies - 1 average
Negate
7 copies - 0.88 average