Instructions
Navigate to the Potions classroom in Hogwarts. Walk into the second room through the door on the right side of the room.
Hold "C" to open your spell wheel. Pick "Reducto" to switch to that spell. Press "Z" to cast the spell on the silver box beside the entrance of the room, unveiling a golden cauldron.
Press "Z" beside the cauldron to drink the polyjuice inside and select any Hufflepuff character, such as Cedric Diggory, to transform into that character.
Walk up to the nearby painting as the Hufflepuff character and speak to it, causing a green key to appear. Switch to your Wingardium Leviosa spell and press "Z" on the key to insert it into the lock on the right side of the room.
Activate the golden cauldron again and select Griphook as your character. Cast Wingardium Leviosa in the water to the right of the cauldron, which automatically assembles gears inside the water, causing the nearby snake head to turn and drop a key. Press "Z" on the key to insert it into the lock.
Activate the golden cauldron once more and select Hermione as your character. Stand in front of the nearby bookcase and press "Z" to arrange the books according to the diagram shown onscreen, unveiling the third and final key. Press "Z" to insert it into the lock, unlocking the gate and revealing a door.
Exit through the door and press "Z" to arrange the blocks on the floor, making a staircase. Climb the staircase all the way to the top to find an orange chest.
Switch back to the Reducto spell and press "Z" on the orange chest, exploding it and rewarding you with the Professor Snape character token.
Press "Start," then select "Leaky Cauldron," followed by "Yes." Exit through the north gate when you arrive to enter Diagon Alley.
Enter Madam Malkin's Robes and purchase Professor Snape for 250,000 studs, the in-game currency.