The power that erupted from the Harmony Suit was new for Izuku to feel. It wasn't just brightness—it was pure energy, the force of the forge refined and concentrated through the mechanisms of the suit. The shadows closest to him simply vanished, their forms dissolving like smoke on a breeze.
The initial shadow remained.
As the light faded, Izuku saw it clearly for the first time. Where its minions were vague, undefined things, this creature was shaped. It carried darkness as a cloak, but underneath that something almost human. Almost.
"Fascinating," it said, its voice stilted in Izuku's mind. "So much power, contained in such a small package."
Aizawa's capture tool slapped out and went through harmlessly in the form of the shadow. "Midoriya, keep focus. Don't get sidetracked!"
The shadow laughed—a laughter that was like breaking glass. "Your tool won't damage me, Eraserhead. Any of your oddities won't. I've gone beyond such things."
"Maybe," Izuku said, preparing for another blast through the armor. "But I'm not using a quirk."
The shape of the shadow shook with interest. "No. You're using something far more ancient. Something that had best have been left where it lay." It took a step closer, and the air around it seemed to become darker. "Did they tell you what it really is, this power that you possess? Did they warn you of what it costs?"
Doubt crept into Izuku's mind, but he pushed it away. "You're attempting to mess with my head. It won't work."
"I'm already inside your head," the shadow replied. "I've been since the moment you accepted the forge. Did you think those nightmares belonged to you?"
Momo stepped forward, her staff snapping with energy. "Don't pay attention to it, Izuku! It's attempting to—
The shadow raced more quickly than the mind could grasp. A second before it had been yards off, it suddenly materialized before Izuku, its obscurity impinging against the face of the shining suit. The forge convulsed wildly, unleashing explosions of energy around the plaza.
"Mei!" Izuku called into his comms. "What is it?"
"The readings are haywire!" Her voice filtered through barely louder than the noise. "Something's interfering with the power stream. You need to—" The transmission was cut off in a bellow of static.
The presence of the shadow began to seep into the joints of the Harmony Suit, testing for weaknesses. Wherever it touched, Izuku felt cold seeping in deep, cold gnawing at him.
"The forge knows me," the shadow replied, its voice now everywhere at once. "We are old friends, it and I. Older than you can even start to think."
Izuku tried to activate the suit's defenses, but the controls were sluggish, unresponsive. The cold was spreading, creeping up his chest where the heat of the forge burned brightest.
"Away from him!" Momo shouted, cracking her energized staff. It struck the shape of the shadow, and it recoiled slightly—enough for Izuku to retreat.
The shape of the shadow solidified again, but now it had something added to it. Something that gnawed.
"Ah," it said, as if pleased. "Now I understand. The suit, the training. you really think you can control it. How quaintly innocent."
It lifted what might have been an arm, and shadows began to congregate in the air around them.
"Let me demonstrate to you what the power of the forge truly is."
The other shadows charged forward en masse, their bodies merging into a wave of darkness that towered over them. Aizawa tugged on Momo, pulling her back, but Izuku remained still, the light of the Harmony Suit thumping in time with his heart.
As the shadow wave came cascading down over him, his mind cut through his fear like crystal: This was what their training had built up to. This was where they'd determine if they had done enough.
The heat of the forge raged through him, and Izuku steeled himself.