Sublime Epiphany If you enjoy casting big counterspells, you cant do much better than Sublime Epiphany
Izzet has plenty of creatures that stick around and draw cards continuously, like Jori En, Ruin Diver, Jhoira, Weatherlight Captian, and Izzet patron, Niv-Mizzet, the Firemind
For one, I think that Detention Sphere will be good for quite some time due to its flexibility, and the same goes for Azorius Charm
It could also buy you enough time by unsummoning a full horde of attackers against your slow board, allowing enough time for you to catch-up blockers to your opponent's fast start
Choice is a wonderful thing, but many beginners appreciate simplicity when it comes to learning a new TCG
It can even be used to put some damage on a high-toughness creature ahead of first strike damage to take down large targets in combat, effectively making her a nine power first-striker when you have five mana up