Most played cards in Izzet:

2 Decks
Neutralize
8 copies - 4 average
Mystical Dispute
7 copies - 3.5 average
Frantic Inventory
4 copies - 2 average
Opt
4 copies - 2 average
Jwari Disruption
4 copies - 2 average
Bonecrusher Giant
4 copies - 2 average
Lore Drakkis
4 copies - 2 average
Fire Prophecy
4 copies - 2 average
Storm's Wrath
4 copies - 2 average
Sprite Dragon
4 copies - 2 average
Spikefield Hazard
4 copies - 2 average
Cinderclasm
4 copies - 2 average
Brazen Borrower
4 copies - 2 average
Scorching Dragonfire
4 copies - 2 average
Blazing Volley
4 copies - 2 average
Improbable Alliance
4 copies - 2 average
Shredded Sails
4 copies - 2 average
Blitz of the Thunder-Raptor
4 copies - 2 average
Soul-Guide Lantern
3 copies - 1.5 average
Negate
3 copies - 1.5 average