Thanks. Why do you think 18?
There's a formula to these things. Not factoring in home court yet, Duke is about 20 points better than us per 100 possessions according to the analytics which is heavily used when setting lines. Both teams play pretty fast so this game estimates to finish at around 75 possessions (D1 average is 68 per game). So:
20 x .75 = 15
On a neutral court Duke would be 15 point favs over us, which is about the same as it was last year going into our game against them. Factor in a 3-4 point home court edge and you get a 18-19 point line at Cameron and about a 12 point line at MSG.
That was an oversimplified version of how a line is made so my guesses won't always be exact as there could be other variables in play that could move the line a couple points. Games with this big of a spread are more difficult to nail down. I wouldn't be surprised if the line opened and/or closed anywhere between 16 and 20