Avalon giggled to herself, scheming and planning while fellow students were busy eating. They didn't know, but she had a big surprise planned for them all to see. As soon as she felt the moment was right and the timing perfect, she cleared her throat and walked up the aisle to face all four House tables.
"Hello, everyone," she began. "Some of you probably know, some of you probably don't, but today is one very special day."
She let it sink in as the quieted murmurs began to race around from all sides of the room.
"And everyone knows," she continued, "that special days should be specially celebrated." Her smile widened as she thought of what she was going to do. "So what day it is today, you ask me? Well..."
Using her innate magic, Avalon summoned a fair sized shard of celestite, a brilliant translucent sky blue-colored crystal. It is widely known for its beauty, but also for one other property that made it a must-have at sacrificial bonfires: when thrown into the fire, it gave the flames a beautiful deep red hue. Being an Incaendefacio, Avalon had something along those lines planned for her surprise. But not to set the Great Hall on fire, I assure you.
"...Happy Birthday, Headmaster Leo!" she proclaimed, and threw the celestite shard high into the air. Then, taking her wand, she aimed its maroon oakwood tip towards the crystal.
"Elementus Fire!"
A torpedo shaped flame zoomed its way through the air to meet the celestite. The moment it connected, the fire heated the crystal and broke it into millions of different pieces. Those pieces turned red, a deeper red than any vermillion, and produced the effect of a big red firework.
The firework occurred above Avalon's head, and would fade down on the rest of the Great Hall in harmless sparks. She had practiced this maneuver so many times by herself that it was only natural that she did it right. Her smile became wider as she looked at the Headmaster and gave him a polite bow.