In his current state of absolute focus, Harry was completely oblivious to any of the events happening both in and around his body. He wasn't paying attention to any of it… Instead, his entire world and everything in it had become extremely small, specific and focused. He'd cast aside everything else but a desperate need to force his magic passed that bottleneck and the tension that he could feel building up inside of it. His focus was so singular in its intensity, he never even noticed the wild maelstrom of magic that was swirling around his body.
He also didn't notice when a thick but translucent green light began to emerge from within his torso, only to sink back inside of him over and over. The radiant green light bucked, strained and bubbled out of Harry's body, burning random patches of his skin within an uncontrolled wellspring of chaotic power.
From a place located deep within his consciousness, Harry's magic repeatedly broadcast a sense of extreme danger and nearly panicked desperation. It screamed at him that he couldn't hold anything back because he was fighting a life or death struggle. Despite the fact that he'd never felt his magic attempting to make contact with him before, Harry felt the connection and recognized it for what it was. His magic was crying for help from the depths of his very soul.
With a long, low growl of absolute determination, Harry poured every ounce of magic he contained into both his spell and the bottleneck that was stopping it. As he became increasingly in tune with his magic, he was willing to burn himself to cinders if it meant completing his task. Over a single timeless moment that seemed to last forever, the magical pressure buildup grew exponentially, along with the searing heat centered within his body.
Where at first the lava-like heat had centered mostly in his hand, now it was all over his body, as if he were burning himself alive with his very own magical essence. Then, finally, when the tidal wave of magic that Harry was channeling felt like it was going to tear him to pieces, the barrier finally burst!
BOOOOM!
Instantly and with a deafening crash of sound, Harry's magic rushed out from within his body to fly out in every direction. It was as if his magic was hundreds of tons of water that had been contained inside something as small as a coke can. In a single instant, a perfect dome of brilliantly bright, green colored magic, exploded outwards and away from Harry's body, leaving him standing in a crater of crushed earth and debris.
As the dome of power exploded outwards, a black and smoky wraith was forcefully ejected from within Harry's scar, only to be launched directly in front of him. The wraith screamed its fury, as it repeatedly tried to fly back towards Harry, but an ongoing stream of magic continued to push it back and away. Then, as the dome thinned out and spread, a translucent green shockwave continued off into the distance in every direction.
When the shockwave hit Hermione, who was standing just a little over eight meters to Harry's left, it knocked her clear off of her feet and about three meters through the air.
In the split second that followed the explosion, the Patronus Charm that Harry had been failing to cast all year finally succeeded. The tip of his wand became the epicenter of a laser light show of dazzling white light, as an absolutely titanic Corporeal Patronus was launched into the air.
The Patronus emerged from the wand at the speed of a bullet and immediately moved to defend its master. The massive stag slammed into the screaming, furious, wraithlike monster, instantly vaporizing it as if it was made of nothing but cobwebs and dust. The wraith didn't even manage to slow the Stag Patronus down as it continued to gallop towards the attacking Dementors.
After flying across the water in less than two seconds, the stag smashed into the Dementors like a high speed bowling ball through pins. It was violent enough that Harry could have sworn he saw some of the Dementors disintegrate during every massive impact of its horns. Then, when the Patronus began circling the two newly unconscious people on the other bank of the Lake, its aura was so large that it managed to create a full dome of protection. Finally, the Stag started radiating huge bursts of bright light outwards that carried a sense of pure joy and saint-like benevolence.