Rowan threw everything he had. Stupefy, Flipendo, Diffindo, Bombarda. Every spell hit the Knight and every spell was absorbed. The glow grew brighter with each impact. The Knight took a step forward with each feeding, the frost on the ground spreading outward from its feet, and the cold intensified until Rowan's teeth were chattering and his wand hand shook.
The sword came again. Rowan dodged left and his foot slipped on the frost and he went down on one knee. The blade passed close enough to his head that he felt the cold of it in his skull, a sharp, piercing ache behind his eyes.
He rolled and cast Incendio from the floor, a sustained blast, desperate. The Knight walked through it. The fire wrapped around the armour and disappeared and the Knight didn't slow down.
Rowan scrambled backward down the stairs. The Knight followed for three steps and then stopped. It stood at the top of the staircase, sword lowered, the glow behind its helm dimming slowly. It watched him retreat. Then it turned and stepped backward into the ice door and the surface closed over it and it was gone.
Rowan sat on the stairs with his back against the frozen wall, breathing hard. His robes were stiff with frost. His wand hand was shaking from cold and spent adrenaline. The warming charm he cast this time lasted longer, away from the door, but the chill had settled into his bones.
Peeves had been right. Everything he knew wasn't enough.
He went to the library that evening and pulled every book on animated guardians, enchanted armour, ice magic, and defensive constructs. He read until the library closed and then continued in the common room, working through the stack while Iris studied across the table.
She glanced at his reading material twice but didn't ask. She was still waiting for him to explain what had happened on Thursday, and the fact that she hadn't pushed was Iris being patient, which meant she was going to push eventually and it would be worse for the delay.
Saturday morning. The stacks had given him nothing useful. The animated armour in the books responded to standard countercurses, which the Knight clearly didn't. The ice magic texts described enchantments that could be melted with sufficient heat, which he'd already tried. Nothing in the standard collection addressed a guardian that absorbed offensive magic and grew stronger from it.
He went to the Restricted Section after breakfast, while the library was empty. His access from Hecat, granted second year for duelling research, still held. The rope barrier parted for him.
The air on the other side was colder than the main library, the way it always was. He'd assumed it was the stone, the thick windowless walls sitting deeper in the building. The chill settled against his skin as he walked between the shelves.
The books in the Restricted Section were still different. They didn't only sit on shelves. Some of them breathed. One growled when he reached for it. Another had a chain through its spine that rattled when he pulled it out.
He found what he was looking for in a slim volume bound in dark leather, wedged between two larger books on cursed objects. The title was stamped in tarnished silver: Ignis Maledictus: A History of Cursed Fire.
The book opened easily. The first chapter was a taxonomy of magical fires. Standard fire spells, Incendio and its variations, produced flame that behaved according to known physical and magical laws. It burned fuel, consumed oxygen, and could be extinguished.
Cursed fire was different.
The chapter described three kinds. Gubraithian fire, which burned eternally but was not destructive. Ashwinder fire, a byproduct of magical neglect. And Fiendfyre.
Fiendfyre. Cursed flame of immense power, capable of destroying virtually anything, including objects enchanted to resist conventional magic. It burned through protective enchantments, consumed cursed objects, and could not be extinguished by any known counterspell. It took the form of monstrous creatures, serpents and chimera and dragons, and it had a will of its own that resisted the caster's control.
The text was blunt about the danger. Of the twenty-three recorded attempts to cast Fiendfyre described in the volume, nine had resulted in the death of the caster. Four had caused destruction so widespread that entire buildings were consumed before the flames could be contained. The most recent recorded use was by a dark wizard in 1747 who had destroyed a Goblin-warded stronghold and himself in the process.
Rowan read the passage three times. An ice guardian that absorbed every spell thrown at it. A fire that destroyed anything, including objects enchanted to resist conventional magic.
He could see the logic. The vault was designed so that the only way through was a spell most wizards would never learn and couldn't control if they did. The cost of entry was the willingness to use magic that could kill you.
He closed the book and put it back on the shelf.
He wasn't going to learn Fiendfyre. The spell was classified as dark magic for a reason. Nine dead casters out of twenty-three attempts. A fire with its own will that resisted control. Even Grindelwald, who would one day master it, used it as a weapon of war, something you unleashed when you no longer cared what it consumed.
Rowan left the Restricted Section and walked through the empty library and down the stairs and out into the morning. The grounds were grey under an overcast sky. Iris, Lawrence, Poppy, and Edmund were meeting him at the forest edge in an hour.