The usual dose of Trigger could enhance a quirk by a multiplier of 2. That of the enhanced version was 16. And if you brought in consecutive dosing ... you got this mess.
Muscle bulging and contracting following the rhythm of blood pressure, blood-shot eyes as more blood rushed to the brain to cool it down, the heart beating at 200 bpm. If not for the body modification done by his sensei, Shigaraki would have been dead from drug overdose from the first injection. Three injections of enhanced Trigger exploded the quirk factor inside his body. The ballooning mental pressure almost rendered him a vegetable but this was something he needed to do to show the wretch what the consequences were.
With increased brain activity came the hastened perception of time. A punch from Re Destro was aiming for his heart, intended to pierce through the rib to cleanly dig out a hole. The condition for the man's quirk seemed to be emotion, and the sign is the growth of the birthmark on his face. Now the thing had covered all of Re Destro's face so this must be his full power.
Facing such a fast blow, what floated inside Shigaraki's brain were two things:
To ignore the basement beneath to prevent allies death To destroy everything else.
But the usual decay from Shigaraki Quirk left dust piles that could bury the basement... unless he decayed the dust down to its atoms. And if he could reached the atomic scale, why not went further down to subatomic scale? But control was still the priority here... If this is the city's main attraction then others could be warnings.
And with the full power of drugs and quirk, Shigaraki thought:
"Decay."
And thus, nothing remained, even ddust.
Everyone inside Deika City was having a great day working to contribute to the cause of their great leader Re-Destro when they noticed that the horizon had become empty. The tallest building in the city, the Detnerat headquarter disintegrated in real time. Debris rain should be the sight but nothing was falling down. Everything was reduced to dust before being whisked away by high-rise winds.
The destruction spread downward through the glass panes and the structural steel beams. Not long after the top floor had become one with the air, the pavements around the building cracked and crumbled away. The effective range continued outward, not sparing any structure or people.
Soon, citizens began screaming. But as soon as the scream came, they disappeared. Some tried to fled to the sky with their quirks but the decay did not have a quick symptom. The loss of nerves following the decay left the victims begging for release as more and more of their body failed to response to the brain. The wilting muscles fell off and dried out like sand, surrounding the body to the elements.
Contrary to the probability, the most healthy, living person inside that devastating AOE attack was the one closest to the center. Re Destro's instinct told him to jump backward through the windows. But what came up must also came down. Re Destro could feel his lower torso dying in real time when he landed. But with a sharp piece of reinforced glass he gotten from the jump, he cut the parts below the knees, wedging the blade into the sockets and ripped straight through the ligaments and muscles.
The stress and adrenaline combined into a thunderous strength, preventing Re Destro from fainting due to shock. The gained height was barely enough for Re Destro to survive, but his gaze remained empty seeing the radius of the attack. Over one fifth of the city had been reduced to nothing, leaving only a fine layer of residue dust in place of infrastructure and human lives.
"Is the view wonderful, Re Destro-san."
And the salt rubbed into the wound was that smug expression of the perpetrator, that wretched successor of All For One. But unknown to Re Destro, Shigaraki was on the verge of collapse. Pushing his quirk factor through a drug overdose situation left it temporarily unavailable to him. But the 'negotiation skills' learnt throughout the years propped him up for a bluff.
"I am willing to share this scenery to more people in Deika city. But I still need to hear the opinion ... of you, Re Destro."
The man was thinking amidst the searing pain beneath. He could muster any more juice, his body was failing him and medical aid was much needed. And the pesky HSPC agents aiming for his domains ...
While Re Destro was slowly making up his mind, Shigaraki was sweating cold sweat inside. From the horizon, he could see a coiling mass making its way toward their location. The only reinforcement he would be having was a portal escape from Kurogiri. He could not unleash the hibernating Gigantomachia freely as the titan would ruin any chance of underlings. Because of that, he could only bet on a change of mind.
"... We follow the strong and the free. That is what our belief is. Very well, my force will join yours."
'This kid could unleash such destruction ... there are possibility of more powerful meta ability users like him over there. I can guide them toward a rebellion and self-sabotage.'
'This man ... is power-hungry. So fast to surrender without even punching another time. His face is calm, most likely calculating the gains and losses. If it has been me, I would have already injured the one before me. I can guess that a knife is destined to be in my back in the future. Still a good deal. And about that approaching ice block...'
Shigaraki brought his arms toward the horizons, the sliver of recovered quirk factor flared up. He could kill the enemy but the one stopping both sides needed to be Re Destro.
Seeing the familiar sight of his most loyal soldier, Re Destro struggled to stand up on his knees and waved his hand. Now looking closer, an ice serpent burrowed its way through the sky before landing right in front of the pair. The serpent was ready to crash down onto Shigaraki if it had not been for Re Destro's signal.
He landed in front of them, a man wearing a thick fur coat despite the smoldering weather.
"Supreme Leader! Is he the one behind this destruction?"
"Yes... but it is merely a bit of disagreement during a negotiation. Let me introduce this man to you, Geten. He is Shigaraki, a representative of a more powerful meta ability user. He is sent here to recruit the meta-liberation army into the group."
"Nice to meet you, Geten-san. My name is Shigaraki. This level of destruction is indeed my mistake. I'm willing to help your city regain its luster. Now, about the rebuilding fee of the main control tower belonging to Detnerat. Inc, let us ..."
Shigaraki continued to spew business jargons. Re Destro could follow and he admitted that the kid had a solid plan. But for Geten, a primary school dropout, he could not understand any thing.
"Shigaraki-san, let us converse at a later time. We need to do post-disaster operations."
"Yes, let us meet at a later date. You can contact me via this burner phone. I know about your IT man, Skeptic. So don't try to pry too much, can you?"
"Of course of course, how could I do such thing to our ally."
"Kurogiri! Send me to Doctor, right now!"
After returning via Kurogiri's portal, Shigaraki collapsed onto the newly-sweep floor. The adrenaline had finally been used up and Shigaraki could not endure the feeling of his heart rupturing and his organs failing in real time.
Seeing the young master in such pain, Kurogiri immediately dropped a wine glass he was cleaning and teleported the teenager to the underground lair of the Doctor.
"Kurogiri! What are you doing here?"
"Young Master overexerted himself. Heavy injuries. And about Mendel and Giran ..."
"They are getting better. The man suffered from severe torture but not something I cannot save. The problem is the PTSD afterward. And for Mendel, the girl is feisty. Her quirk automatically protect her body. Oh how wonderful it would be if I can freely dissect her."
"Please take care of the three of them. And Master, how is he?"
"He has already gone to other countries to gather allies and resources. He lets me know of a possible quirked weapon. But return for now, Kurogiri. If Master did not share the information with you, he will share it at a more appropriate time."
"Yes, Doctor."
Before leaving through a portal, Kurogiri spotted a gigantic tank hosting a black sphere. He then teleported a canister into the sphere, cutting it in half with the closing portal before getting out of the underground lab.