Masquerade Ball: Costumes!
Okay, guys. To get into the ball, you must be in costume and you must be wearing a mask.
YES, even those who are there on official business (the Aurors & Hitwizards, primarily) will need to be in costume. YES, the DEs need costumes, as they will be at the ball before changing into their Robes And Masks Of Eating Death. And yes, you want your DEs to be at the ball -- it's a perfect excuse to get patched up at St. Mungo's after the fact: you were an innocent bystander at the ball when you were ATTACKED by those HORRIBLE TERRORISTS.
HOWEVER. Aurors & Hitwizards (including trainees) will be wearing these masks. They already know that their masks will be provided. Nobody knows what they look like yet, and nobody will know until they show up at the ballroom and are given their mask.
SO! Are your characters going to the ball? What do their costumes look like? This is both so that nobody repeats (yes, that might happen in real life, BUT THIS ISN'T REAL LIFE), and also so that we can figure out who won the various costume contests! Yay!