Most played cards in Grenzo, Havoc Raiser:

3 Decks
Cavern of Souls
3 copies - 1 average
Skullclamp
3 copies - 1 average
Lightning Bolt
3 copies - 1 average
Goblin Ruinblaster
3 copies - 1 average
Chandra, Torch of Defiance
3 copies - 1 average
Chain Lightning
2 copies - 0.67 average
Sudden Demise
2 copies - 0.67 average
Pillage
2 copies - 0.67 average
Fiery Confluence
2 copies - 0.67 average
Smash to Smithereens
2 copies - 0.67 average
Collective Defiance
2 copies - 0.67 average
Rolling Earthquake
2 copies - 0.67 average
Chrome Mox
2 copies - 0.67 average
Smuggler's Copter
2 copies - 0.67 average
Incinerate
2 copies - 0.67 average
Exquisite Firecraft
2 copies - 0.67 average
Flame Slash
2 copies - 0.67 average
Goblin Piledriver
2 copies - 0.67 average
Mizzium Mortars
2 copies - 0.67 average
Shattering Spree
2 copies - 0.67 average