Douglas waved his wand again, and a huge glass tank appeared at the front of the classroom.
The students who knew him felt their hearts sink. If Professor Holmes, who usually snapped his fingers, was using a wand to summon something, today's lesson was definitely not going to be simple.
Dozens of strange deep-water plants floated in the tank.
They were translucent all over and deathly pale. Each had a main stem as thick as an arm, covered in small, tentacle-like branches.
Strangest of all, a fist-sized fleshy sac grew at the roots of each plant, expanding and contracting like a beating heart. Every beat released a faint blue glow.
"What is that?" a student couldn't help asking.
"Good question."
Douglas nodded approvingly.
"This is Abyss Soul-Sucking Algae, a deadly magical plant that only grows in extremely deep water. It's far more dangerous than those little things you studied in your first year."
He tapped the glass with his wand.
"See that pulsing fleshy sac? That's its magical heart. Each beat releases a special pulse of magic that disrupts the flow of a wizard's magic, making spells less effective."
Douglas continued.
"What's more troublesome is that if you hit it with an ordinary Severing Charm, its tentacles will sense the magic and strike back three times as fast. And for every tentacle you cut off, its magical heart beats faster, making the interference stronger."
There wasn't a sound in the classroom.
"...Then how do we deal with it?" Cedric couldn't help asking.
"This question is free points," Douglas said, curling his lip. "Can't you use your brains? Do you think every enemy you encounter in the future will be a standard model straight out of your textbooks?"
He walked over to the tank and pointed at the most active clump