Collect the indicated number of crests to unlock the corresponding bonus.

Bonus	Crests
Dungbombs in prank boxes around Hogwarts	21 Hogwarts Crests.
Exploding Cauldrons in prank boxes around Hogwarts	48 Hogwarts Crests.
Love Potion in Potions Club	98 Hogwarts Crests.
More health in duels	8 Hogwarts Crests.
Even more health in duels	71 Hogwarts Crests.
More mini-crests with each cast	129 Hogwarts Crests.
Score boost in flying events	38 Hogwarts Crests.
Two Player Dueling Pack 1: Draco and Luna	3 Hogwarts Crests.
Two Player Dueling Pack 2: Crabbe and Goyle	29 Hogwarts Crests.
Two Player Dueling Pack 2: Training Ground Dueling Arena	14 Hogwarts Crests.
Two Player Dueling Pack 4: Paved Courtyard Dueling Arena	113 Hogwarts Crests.
Two Player Dueling Pack 4: The Transfiguration Dueling Arena	59 Hogwarts Crests.
Two Player Dueling Pack 5: Ginny and Hermione	84 Hogwarts Crests.