Unlock castle gates:
To unlock the Castle Gates multiplayer dueling area, go to the rewards menu and enter RIGHT, RIGHT, DOWN, DOWN, LEFT, RIGHT, LEFT, RIGHT, LEFT, RIGHT, START.
Hogwarts crest rewards:
Collect the listed number of Hogwarts Crests to unlock the corresponding bonus.
3 hogwarts crests - Two Player Dueling Pack 1: Draco and Luna
8 Hogwarts crests - More health in duels
14 hogwarts crests - Two Player Dueling Pack 2: Training Ground Dueling Arena
21 hogwarts crests - Dungbombs in prank boxes around Hogwarts
29 hogwarts crests - Two Player Dueling Pack 2: Crabbe and Goyle
38 hogwarts crests - Score boost in flying events
48 hogwarts crests - Exploding Cauldrons in prank boxes around Hogwarts
59 hogwarts crests - Two Player Dueling Pack 4: The Transfiguration Dueling Arena
71 hogwarts crests - Even more health in duels
84 hogwarts crests - Two Player Dueling Pack 5: Ginny and Hermione
98 hogwarts crests - Love Potion in Potions Club
113 hogwarts crests - Two Player Dueling Pack 4: Paved Courtyard Dueling Arena
129 hogwarts crests - More mini-crests with each cast
Easy duels:
Cast Levi Corpus or Petrificus Totalus, then charge your Stupefy until it chimes twice and release it. This will results in a one hit kill. This does not work for Fenrir Greyback.
Locked gate shields:
When there is a shield behind a locked gate, use Wingardium Leviosa and hit it into a wall to break the shield. Pick up the pieces, then repair them and you will have a shield.