Most played cards in Goblins:

1 Decks
Mishra's Factory
4 copies - 4 average
Waste Not
4 copies - 4 average
Liliana of the Veil
4 copies - 4 average
Quest for the Nihil Stone
4 copies - 4 average
The Rack
4 copies - 4 average
Shrieking Affliction
4 copies - 4 average
Blackmail
4 copies - 4 average
Duress
4 copies - 4 average
Dark Ritual
4 copies - 4 average
Hymn to Tourach
4 copies - 4 average
Ensnaring Bridge
3 copies - 3 average
Pithing Needle
3 copies - 3 average
Grafdigger's Cage
3 copies - 3 average
Perish
2 copies - 2 average
Null Rod
2 copies - 2 average
Geth's Verdict
2 copies - 2 average
Inquisition of Kozilek
2 copies - 2 average
Thoughtseize
2 copies - 2 average