Those cards are Brainstorm, Sol Ring, Kodama's Reach, the Signets, Fire // Ice, and Cultivate
Exile-based interaction has quite a few advantages over removal spells that destroy their targets thanks to near-permanent removal and its ability to skirt indestructible
As a general rule of thumb, if you're able to keep Bilbo as your ringbearer, it acts as a "Life Insurance Policy", knowing you'll have a ringbearer even if Bilbo is killed, and as a bonus increases likelihood of treasure creation
His article includes the quote "it appears that the two, three and four-mana slots are where the majority of your spells should be." Frank is right, if what you're looking to do is optimize your curve and minimize variation in gameplay, which is precisely what competitive players want to do
When you combine the awesome power of red with the inquisitive and insightful nature of blue, you get Izzet, the color combination of your classic mad scientist