Harry had a deep impression of this magical creature. At the end-of-year exams last school year, Remus Lupin had used Grindylows as one of the tests.
He remembered clearly that Wizet had directly transfigured a bridge, easily passing the Grindylow test in an impressive fashion.
Even when Grindylows tried to attack Wizet, he had dealt with them using the Extraction Charm, neutralizing their assault.
"Grindylows!" Harry said. "I remember that you can use the Extraction Charm against them."
"There's one thing to keep in mind..." Wizet said. "The Extraction Charm works differently underwater."
"When used underwater, the Extraction Charm changes form. It manifests as a jet of high-temperature water."
Some of Selina Pendragon's combat memories involved fighting underwater, which was why Wizet reminded Harry and the others that the Extraction Charm manifested differently beneath the surface.
"That makes the Extraction Charm seem dangerous, doesn't it?" Harry reasoned. "If a Grindylow grabbed your foot and you used that spell... you'd definitely get burned, wouldn't you?"
"Wait, that's not right... That effect actually seems pretty good!" he realized. "Since the Extraction Charm works that way, we might as well use it as an offensive spell!"
Cedric agreed. "Not just against Grindylows. The Extraction Charm should work well against other underwater creatures too."
"Right! I also found a way to breathe underwater." He pushed <Magical Water Plants of the Mediterranean and Their Properties> forward so everyone could see it.
"I also really agree with Wizet's approach to solving the riddle, so we can consider bringing this along before the task begins..."
He pointed at a passage in <Magical Water Plants of the Mediterranean and Their Properties>. "This is an aquatic magical plant called 'Gillyweed'..."
<Magical Water Plants of the Mediterranean and Their Properties> also included an illustration of Gillyweed. At first glance, it