"But without understanding it, how can you even create it?"
That was the most basic of creation magic. To create an explosion, a mage must first understand it. The primitive elements, as Savine explained, a mage could create without much trouble, but to create more complex spells, they must have a deeper understanding of what they're doing.
Since that was the case, how can Savine create a cigarette out of her imagination?
"If that's the case, how can the Magi create plagues, bombard you with thunderbolts and make you see illusions? Do you think they understand these concepts and thus are able to create spells of them?"
"…"