"You know Dasher and Dancer,
and Prancer and Vixen,
Comet and Cupid,
and Donner and Blitzen,
But do you recall
The most famous reindeer of all?"
But? But? That conjunction just doesn't work there. If anything, it should be and.
“But” would work if it was saying you know all the well-known reindeer, and then it asked, “but do you remember this obscure one?” This is like saying, “You know the Seine, you know Notre Dame, you know the Moulin Rouge, and you know Montmartre, but do you recall The Eiffel Tower?