Destroy 50 Devil's Snare plants

Defeat Harry (as Voldemort), in the Graveyard

Defeat Quirrell in the Quirrell boss fight, using Voldemort

Scare 20 students using a ghost character

Buy every version of Voldemort (Quirrell/Tom Riddle/Voldemort)

Rescue all students in peril

Complete all the LEGO Builder tutorial levels.

Buy the entire Weasley family

Turn the sound down to 0 and music off in the options menu whilst in the library

Collect all of the house crests in Year 4

Reach level 10.

Hide in a barrel as Snape

Defeat 20 enemies with Fang