Kevin's water shields went up fast.
The first wave of blue fire hit them and washed off in a hiss of evaporated water. Good. His shields had improved since Malfoy Manor — thicker, layered, better at distributed resistance rather than rigid deflection.
But the heat was different from last time. There was something missing from it. He couldn't quite name it yet, but something in the quality of the magic felt — not reduced exactly, but approximate. Like a copy made by someone who understood the original.
"Kevin, I gave you an opportunity," Grindelwald's voice came from the fire. "I told you to step back."
"I'd prefer to talk." Kevin rolled sideways as a lance of blue slammed into the spot where he'd been standing. The crowd was scattering now — Death Eaters Disapparating, a few of the braver ones drawing wands, others simply running. "We could be having tea right now! My place, or yours — very flexible on the venue!"
A water spike came down at him from above — the ambient moisture of the Mirror World spun into something pointed and fast. Kevin didn't dodge. He absorbed it through his shields. It hit like a concentrated jet and still barely touched him.
Grindelwald had underestimated his physical durability. Most people did, the first few times.
He sent out his Freezing Array in a wide arc, catching the last of the Death Eaters who hadn't yet managed to Disapparate. They dropped where they stood. That was something, at least — the Aurors would be through any moment.
Then lightning came down.
No warning. No sound of it gathering. Just the crack and the blast.
Kevin was three metres to the left of where it struck, having moved on instinct. He looked down at his cloak.
The right side, from shoulder to hem, was burnt to charred ribbons.
He felt a spike of genuine grief.
"Hermione made this," he said, loudly, to the fire.
The fire didn't respond.
He looked at what remained of the cloak for one more second. Then:
"Divine Strike Without Shadow."
The slashes went out in a fan — invisible, radiating in every direction, crossing and recrossing — and hit the blue fire wall simultaneously from every angle at once. The fire didn't have a centre to retreat to. It simply came apart, each tongue extinguished by a cut it couldn't track.
The stone platform cracked neatly in every direction. Rubble settled.
No Grindelwald in the fire.
Kevin turned.
A hand closed on his shoulder from behind.
He felt it coming a half-second before contact — the pressure change in the air, the slight displacement of something moving fast and silent — and he was already moving. His crowbar came up, Hardening Charm blazing gold along its length, and he swung.
Grindelwald hadn't expected the speed.
The crowbar caught him across the temple and carried through. He flew.
Kevin didn't celebrate. He walked to where the body had fallen and stood over it, bouncing the crowbar once in his palm.
Wrong weight.
The body on the ground had no head. What it had instead was mud, and clay, and a complicated armature of transfigured material, all slowly collapsing back into itself.
Kevin stared at it.
The real Grindelwald had been watching from somewhere else. The whole time.
"You were never here," Kevin said, to the empty air.
The Mirror World gave no answer. But somewhere, he was fairly sure, an old man was quietly amused.