Dumbledore said:
"Then let's change the approach. The Goblet of Fire! Before Halloween, any student who wishes to enter the Triwizard Tournament, no matter who you are, must write your name on a piece of parchment and drop it into the Goblet of Fire. On Halloween, the Goblet will choose the contestants representing the four schools!"
"However, I must remind you that before you submit your names, you need to think very carefully! As I said before, the Triwizard Tournament is cruel and dangerous. Once chosen, no matter who you are, there is no turning back and no withdrawal!"
Chapter 471