Dragon Claw
From UnknowableWiki
Powdered dragon claw is said to be a powerful brain stimulant.
Harold Dingle tries to sell dried Doxy droppings as powdered dragon claw to Hogwarts students before the O.W.L. and N.E.W.T. exams of 1996. Hermione Granger confiscates it. Ron Weasley begs her to give him some until she tells him what the substance really is (OP31).

