Most played cards in Sudden Substitution:

1 Decks
Defense Grid
4 copies – 4 avg
Pact of the Titan
4 copies – 4 avg
Leyline of Sanctity
4 copies – 4 avg
Sudden Substitution
4 copies – 4 avg
Merchant Scroll
4 copies – 4 avg
Preordain
4 copies – 4 avg
Ponder
4 copies – 4 avg
Summoner's Pact
4 copies – 4 avg
Brainstorm
4 copies – 4 avg
Pact of Negation
4 copies – 4 avg
Lotus Petal
4 copies – 4 avg
Forbidden Orchard
4 copies – 4 avg
Force of Will
4 copies – 4 avg
Surgical Extraction
2 copies – 2 avg
Elvish Spirit Guide
2 copies – 2 avg
Scalding Tarn
2 copies – 2 avg
Otawara, Soaring City
2 copies – 2 avg
Ancient Tomb
2 copies – 2 avg
Dress Down
2 copies – 2 avg
Faerie Macabre
1 copies – 1 avg