So this was just something I cooked up in about half an hour of writing. I haven't gone through and edited it, so it's almost certainly quite rough around the edges - however, I wanted to put it up here and see what was thought of it. If enough people like it and let me know, perhaps I'll build a larger story from it... I'm certainly interested enough in a competent Harry fic. Well wishes to you all. :)

5/03/2020: Edited due to a good point raised by Doctor Dandy - magical reserves aren't actually a thing in canon. Not that canon typically applies in an AU fanfiction, where the magical system might be different, but as I didn't specify that, it's a valid and accurate criticism. Therefore, I've edited the piece to remove any mention of magical reserves. :)

Magic crackled in the very air surrounding the two combatants. It sent the hair on Harry's neck standing stiff, and his skin tingled – not unlike the atmosphere before a thunderstorm. Voldemort stood, glaring, twenty paces away, the pits of his snake-like nostrils flaring as he drew up his immense magical power. Harry could sense it roiling like a boiling sea - almost tangible to his physical senses.

Well, two can play at that game, Harry thought.

Harry did the same, pulling his magic to the surface even further, and flaring it out in as big a display of magical strength as he dared. Glass a dozen metres away shattered and turned into sand before it hit the ground, such was the pressure being exerted by the pair. Harry's wand slipped into his hand from its holster, and he gripped it loosely, sinking into a crouch as Voldemort raised his own bone-white wand.

Spells erupted as the Dark Lord went on the offensive, white-hot magic flashing between the two. Harry dodged and weaved between the curses and jinxes hurtling towards him, knowing that he was far outclassed in spell repertoire by Voldemort. His wand flicked, swished and slashed precisely and quickly, shields flaring at just the right moment and rubble soaring into the path of spells he would be hard-pressed to dodge. Harry knew that his chances to return spells would be slim, so whenever he could, he made them count: severing curses, charms designed to cause blindness, intoxication (could the Dark Lord even get drunk? Harry wondered briefly before cutting off that train of thought as a Cruciatus curse rent the air directly over his head), engorgement and other nasty things at his opponent.

Voldemort, Harry mused, was a duellist who didn't move. His utterly gargantuan magical strength ensured that he could put far more into any shield and defense than an attacker could possibly hope to counter, and thus he did not need to worry about dodging. Harry, on the other hand, did nothing but dodge and move. His own Seeker reflexes allowed him to be extremely aware of his environment, anticipating and moving away from the vast majority of spells, and the ones he couldn't dodge he could easily block or counter.

His only advantage lay there. Voldemort wouldn't have such a honed sense of where obstacles and paths in the environment lay, and that was possibly where he could catch him out. It would only work once though – the Dark Lord could sense magic and once he knew of the danger that option would be closed.

Patience, as always.

The ground and air between Harry and Voldemort grew hot and disjointed. The scent of ozone growing stronger as the spells traded grew ever more vicious. Harry sent a blasting curse at his foe, throwing himself to the side seconds later as his curse came back bigger and rippling with black streaks, impacting into a balustrade behind him and sending debris everywhere. Pain blossomed at his hip and he grunted, before twirling his wand and thrusting it towards Voldemort. All of the shattered stone shards from Voldemort's curse came rocketing back towards him, and the Dark Lord was forced to conjure a physical shield, the solid silver surface being marred with indents due to the sheer speed of the missiles.

Harry wasn't finished, however – continuing to twirl his wand, and concentrating on what he wanted to achieve; all of the debris and rubble from their duel took flight, becoming a swirling tornado surrounding Voldemort. Narrowing his eyes, he slashed his wand viciously across himself, the tornado instantly inverting towards the Dark Lord, who thrust his wand overhead and shouted wordlessly, conjuring a barrier of pure shadow that obscured him from sight momentarily.

The shield had saved Voldemort certainly, but not entirely. Several wounds leaking dark blood showed on his limbs, and across his left cheek, but nothing life-threatening. Indeed, he just looked more furious than before.

Shit.

Snarling, the Dark Lord struck back, spells whizzing at almost incomprehensible speeds from his wand, so much so that Harry was forced to rely ever more upon his shielding and conjuring. Even with all of his defensive and reactive ability, it still wasn't enough in the face of Voldemort's onslaught. A grey spell, tinged red snuck through his shielding and struck him upon his left arm, rending it numb immediately all the way to his shoulder.

Shit, shit, shit!

Knowing his situation was dire, Harry threw everything onto offense – disregarding his shields except for the bare minimum, Protego Maxima's and defensive conjurations. Instead, he sent a wave of annoying jinxes and hexes towards Voldemort, keeping him occupied for a moment, which was all he needed. Gripping his wand, he concentrated and harshly yanked upwards while gritting his teeth at the strain of his attempted transfiguration. For a moment, nothing happened, and Voldemort prepared to strike the final blow, drawing upright with his wand glowing ominously green.

Then, the ground trembled violently. A fist made of stone erupted from the floor next to Voldemort and struck him, sending the Dark Lord careening into the wall. The rest of the rock golem's body pulled itself from the floor, looming taller than a mountain troll as Harry nearly fell onto his knees from the effort of creating the beast. He threw a couple of reinforcement charms onto the golem, before sinking onto his haunches and trying to regain his breath. He couldn't see Voldemort through the cloud of dust thrown up by the rock golem, but he could hear the spell-fire as his enemy threw spell after spell at the animated mountain, as the creature slowly made its way towards him, with the instruction 'crush him' in mind. It wouldn't last long, but it bought Harry time – time he needed to execute his original plan of using the environment against Voldemort.

Pushing himself to his feet, he gauged where the Dark Lord ought to be standing, gritted his teeth for one last concerted effort, and concentrated on a spell as he watched his rock golem get obliterated by a dark curse bisecting it from shoulder to hip, ripping through the reinforcement charms as if they were tissue paper.

Accio! Accioaccioaccio!

With a wrenching crash, Harry's spell pulled the entire wall behind Voldemort towards him with startling speed, and he caught sight of widening blood-red eyes just as it impacted upon him.

For a moment, there was nothing but terrible crashes and impacts as the ceiling caved in on that side of the room too. Then, silence.

Harry shifted uneasily, there was too much silence. He raised a shield and set a number of shattered stone blocks circling around him in a whirling barrier. His paranoia was rewarded a moment later with a scream coming from the rubble and an explosion, sending all of the piled rubble hurtling outwards and a giant flaming fiendfyre basilisk came roaring towards him.

Fuck! He had time to think before shouting the activation word for his portkey, knowing he couldn't hope to match Voldemort right then, exhausted, wounded, out of breath and time.

"Hogwarts!" And he disappeared in a swirl of magic, seconds before the fiendfyre crashed upon the spot he'd been standing with a fury that the very stones themselves couldn't withstand, and all that was left of the church was the fading screams of Voldemort's fury and melted slag.