AN: This is a dnd character of Wizard 21 with access to epic-level casting.
The feats he has is Brew Potion, Craft construct, Essence Mastery, Silent Spell, Skill Focus (Knowledge(arcana), Spell crafting, still spell, craft magical arms and armor, craft wondrous items, empower spell, forge ring

Essence Mastery is from Feats book by Alderac Entertainment Group

The adventures mentioned are Savage Tide from Dragon magazine and Bastion of Broken Souls

DND in DC

Chapter 1: the start of the situation

I was Magnus, one of the youngest wizards alive to reach the heights of 9th-circle spells and beyond. I was the one who slew demon prince Demogorgon and stopped his savage tide from ravaging tens of thousands. But most importantly, I was...

"Where in the name of Boccob's boundless books am I?"

... I was also completely and hopelessly lost.

Amongst the strange towers of stone and glass in this strange new world, I stood. My blue eyes peered from under my broad wizard's hat. Taking one look at the flashing lights that decorated the buildings: Golden arches, a smiling redhead, a massive sandwich, I immediately realized something, "I may have severely misworded that [Wish] spell..."

I crafted gear in preparation for my attempt to travel to a different prime material plane alongside taking a fair bit of materials to get a little base going. I had not expected, however, to see that I was currently on the ground surrounded by buildings of unknown designs with the sounds of what sounds like a small horde of people coming from one end. Why are some of them screaming about a clown of some kind?

As for myself... I kept my eyes peeled as I cast an [Magnificent Mansion] and slowly back into its shimmering portal entrance, adorned as it was with lights like twinkling little stars. The only entrance. Much easier to keep an eye on and defend. And as I backed into the safety [Magnificent Mansion], I kept my eyes locked on those Golden Arches. I didn't like the look of them. They looked exactly like the type of runic trap that some evil Wizard would make.

Now that I look at my surroundings, everything seems to have this dull taint of evil. Something or someone has been defiling the city for so long that it seeped into the stones of buildings and the roads themselves.

My eyes narrowed, wary of any shenanigans. With a wave of my robed arms, I used two castings of [Wish] to give myself two [Simulacrums] of myself. Mirror copies of myself marched fearlessly in either direction- their robes billowing behind them as they scouted out the danger. As they formed, I cast [Interplanar Telepathic Bond] on all three of us to communicate with them while they left the [Magnificent Mansion].

The first order of business was getting a few things ready just in case I needed to come back here in a hurry. I comb through my {Blessed Book} to find the ritual for a [teleportation circle]. I go through my {Bag of Holding} to find a metal container sealed with a [Gentle Repose] sigil stamped on its cap. Opening the container, I pull out a decent-sized wad of dried Amber and begin shaving it with my trusty adamantine carving knife.

As I start to finish up the inner magic circle of the [Teleportation Circle] I am given the last bits of information from the simulacrums before they return due to running out of spell slots. The first thing that is startling is that there are no major magic institutions or even another wizard's tower! The second thing was something I could comprehend. This world does have its own heroes and its own villains. The heroes are usually dressed in some sort of single piece of clothing with the villains being much the same. This isn't the odd part; the odd part is that they like to fight in the streets and destroy a large amount of the area during the fight. Given that this world has much more densely populated cities than Toriel, that sounds like a bad habit. The local 'heroes' in this city called Gotham are Batman and his squad of trained people of various ages fight people called things like 'Bane' 'Cat Woman' And 'Two Face'.

Knowing that while the simulacrums rest to regain spell slots, I still have more than enough to do some of my own scouting. Magic sigils explode out of my book as I begin casting a few spells in preparation for combat. The first spell I cast was [Epic Mage Armor] one of my strongest flat defensive spells. Alongside this I cast [Protection From Chaos], [Bull Endurance], [Cat Grace], [Haste], and [Foresight]. I would cast more but I need to have offensive spells ready. With steel determination, I stride forth from my shelter into this strange new world with newfound vigor.
As I exit the portal, I'm greeted by blaring horns and swearing the likes of which would make a nun faint. I leave the alley and see these metal horseless carriages powered by something as far as I can tell. They all seem to want to leave the area and given the speed people are running, it is something disastrous. So disastrous that they don't even notice me or my magnificent hat. I went down the sidewalk for a few moments when I noticed that there was a box that emitted both sound and light. It was also not radiating any magic. How fascinating! The lightbox shows a jester of some kind holding something with another man tied to a device of some kind. He seems to be ranting about something.

"Hello, my fellow Gothamites! Put down your food and clean your glasses, it's time for your regularly scheduled programming! Today's events are as follows. I've hidden 8 bombs all around Gotham with a special 9th one here with me alongside your commissioner Gordon! In 20 minutes, I will be detonating the first of the bombs at random. Could it be here? Could it be at the hospital? I don't know! Hope you can find all of them before they start blowing Batsy! HAHAHAHAHAHAHHHH!"

"…..Some things never change," I mutter as I turn right back to my [MM]. if there is a possibility that this man is the cause of this panic, then he might also be the reason that there is this twinge of evil everywhere. Therefore, I should do this world a bit of service as my first real act here and slay him. With the [teleportation circle] being done, it should be a quick back-and-forth even if it takes a few minutes to slay him. Sigils arrange themselves into a compass as I cast [Discern Location], and by the end, I know where this "Jim" Gordan is. This clown seems to be extremely arrogant if he is willing to stay with the last bomb. With that, I cast a [Teleport Without Error].

I show up right in the middle of the room he was in. The mustachioed man is most likely Jim Gordon who is currently struggling against his binds. The other occupant of the room is another matter. He is a really tall lanky man with bleached skin and green hair. His outfit seems to be a suit of some sort but stained and colored in an ugly shade of purple and green. He has a grin painted on his face and he just radiates pure evil. He even has a bit of a stink that procs my {Necklace of Adaption}.

Yeahhhh ima kill him. He turns to my direction; he jumps back a few feet with an impressive agility I did not expect from this clown man.

"Ah! Where did you come from? Are you one of Bat's little child soldiers? No, you're not in a skin-tight body suit or nothing. What's with the robes? Are you here for the convention? If so you're off by a few miles down losers street. What's with the big hat? Are you cosplaying as Ganando-"

I just cut him off with a thin green beam casting [Disintegrate]. He dared to insult my magnificent hat. He instantly turns to dust piled onto the floor.

Huh.

I know the evil of this potency tends to come back eventually so I begin to cast [Soul Bind] so he doesn't come back. I start to pull out the sapphire I have as a spare when the man strapped to the bomb starts talking to me.

"I don't know what you did to him but you need to get me off this thing. He set this one on a timer and it's going off in two minutes! Look I think he had details on the desk over there. I'll guide you through it but we need to move fast before we are both-"

I cast [disintegrate] on the bomb. It too turns to dust before it can do anything.

"Or you can do that… huh. Okay." since the bomb he was tied to is now a big pile of dust he just shakes off the ropes and gets up. I think he expected me to figure out how to disarm the bomb. Why do something like that when I can just erase the bomb itself? such is the wonder of magic.

"Mind if I ask you a few questions while I get this guy's soul real quick?"

There was a long pause as he just stared at me. Did I say something strange?

"Uh sure but… what do mean by grab his soul real quick?"

"Oh, where I'm from any being that is both evil and feared tends to come back like a rash. It happened enough times that I started just taking their souls so they couldn't be resurrected or anything like that."
"So he is….dead?"

"Yes sir. With no body and now no soul in the afterlife means he isn't going to come back anytime soon."

With that, I finish the casting of [Soul Bind] and just to be safe I also cast [Destruction] as well to make sure that not even ashes remain. With a cheeky (silent) (still) [Detect Thoughts] I try to gather some information from his mind about this clown man. His thoughts are going a mile a minute trying to make sense of this. Did he just expect me to just beat him up like everyone else does? He is also considering… to arrest me? The simulacrums are telling me that there is a tidal wave of happy thoughts coming from the people here in this city.

Okay, so killing him was good? I will need to look into what exactly he was doing to these people but first, I am going to take a nap. I should ask this guy if he needs anything else.

"So are you going to be okay in here? Do you want me to take you somewhere or?"
that seems to take him away from his thoughts as he snaps his head to me.

"No no, it's fine. By now Batman and his robins are done with the other 8 bombs and heading this way. If you have nothing else to do you can stay and answer a few questions?"

I know a damn trap when I hear it. "Nah I'm going to go back and take a nap. Thanks for the offer though." before he can say anything I [Teleport] back as I hear the thoughts of a lot of people sprinting for the door.

As I show up in my MM, I order the simulacrum to set up a [mage private sanctum] just in case. Overall a pretty successful first day in a new universe.