I wanted to add on to this really quickly. The other thing is that different builds accomplish the same goals with different cards. My colorless list can support
Ensnaring Bridge relatively easily because it tends to get rid of cards quickly. I also run
Silent Arbiter as another way to hold off idiots. If you're running C/g,
Maze of Ith and
Candelabra of Tawnos can accomplish more or less the same thing by holding off multiple creatures at the same time. Because I play almost exclusively at sorcery speed, my answers are preemptive:
Thought-Knot Seer and sphere effects for combo,
Karn Liberated for spot removal, for instance.
Part of your build choice should be the general meta where you are and part of it should be what your strengths are as a player. That's one of the great things about the deck: put in the mana engine and then customize it to your liking. I like
Sensei's Divining Top; BoozeCube doesn't. Some U/G builds always have
Trinket Mage; others don't. And so on.