Izzet Affinity is full of cheap colorless artifacts (Mishra's Bauble, Urza's Bauble, Lotus Petal, Mox Opal, Chrome Mox, Chalice of the Void), so Consign to Memory is a one-mana answer that counters those colorless spells outright. It can't counter their blue spells such as Thoughtcast, Kappa Cannoneer, Emry or Council of Reeds, but it can counter triggered abilities, like Urza's Saga's chapter III search or the Cannoneer's and Emissary's triggers. Crucible of Worlds lets us replay sacrificed fetchlands from the graveyard, which helps keep land drops flowing if the game goes long. Back to Basics would hit their nonbasic lands (Seat of the Synod, Urza's Saga, Ancient Tomb), but it also shuts off our own nonbasic lands, so it comes out. Forth Eorlingas! and Gandalf are the cards we can best spare against their proactive artifact curve.