In the book 50 Amazing Cocktails Inspired by Harry Potter by Archie Thomas, Professor Trelawney is represented by a drink called a Crystal Ball. It's a White Russian in the muggle world. We use this drink to represent Ravenclaw.
2 1/2 parts vodka
1 part coffee liqueur
1 1/2 part single cream (half and half for those of us on this side of the pond)
Put ice in a cocktail shaker and add vodka and coffee liqueur. Shake. Strain the contents into a glass with fresh ice. Layer on the cream. Garnish with a cocktail cherry.
Harry Potter and all other characters/places/houses/etc. are the property of J. K. Rowling.