It was a day like any other day for the unicorn. She paced nimbly through the thin threes of the forest verge, sometimes alone and sometimes in the company of others. She knew them all – her friends and relations, though they had no names for themselves she knew them by the sound of their minds, as they knew here and could speak of each other.

In the fading afternoon, when the Unicorn laid in the grass alongside her sister and her sister’s mate, the golden sunlight glinting from their pearl horns, the Stranger arrived.

The Stranger was a human – the Unicorns remembered only enough about them to know that word, for it had been a very long time since any humans had arrived in the vale where the unicorns dwelt

She was not old, nor was she exactly young, though either way the unicorns could not have reckoned it, being unfamiliar with humans as they were. Her hair was black as ebony wood, skin pale and fair, lips crimson as blood. She wore beaten traveling clothes – grey-black robes wrapped shapelessly around her form, a broad-brimmed hat shaded her face, and high boots rose to her calf. She stopped before the Unicorns, leaning somewhat on a tall and rune-etched stave she used as a walking stick.

The unicorn greeted her

Hail, stranger, she said, Why have you come to our glade?

“Why?” The stranger said aloud, seeming somewhat startled at the soft and gentle voice in her mind, “Why, to find somewhere peaceful, where I might stay a while to conduct my work. I hope it would not be an intrusion.”

Be at peace with the earth, the unicorn replied, reciting words she had learned from her mother to tell to outsiders, Drink the cool water, sate yourself with the fruit of the trees and fields and avail yourself of the breeze. Do this only, and you shall be welcome.

“Well,” the strange said, “I shall have need of the water of this land, and its fruits. Perhaps, pretty creature, you could tell me where runs a stream through your home?”

To this, the Unicorn granted the Stranger an image, her impression of the lay of the land, and indeed its waterways as well.

The stranger thanked her strangely, and walked away.

In the days that followed, the coming of the Stranger was the chief matter in the minds of the Unicorns, for it was different than just the turning of the leaves or the mysteries of life that played out before them. The stranger constructed, from magic one would presume, a cottage by the stream, and from it ventured out among the unicorns now and again. She spoke to them carefully, and asked after their nature while here and there dispensing pearls of wisdom that little relevancy held to unicorns.

By and by summer faded into autumn, and the presence of the stranger became something usual, something inoffensive. But in those days, one of the unicorns of the vale went missing, and this was very strange and worrisome. She had been quite young, barely more than a foal – it could have been that she was struck with wanderlust, but then why had she told no other soul she was going? Otherwise, there were few dangers in the vale or near its edges, but there were those few all the same and some tragedy might have befallen her.

The unicorn who had first greeted the stranger had an odd suspicion of the woman, but no evil intent had she ever revealed not even hinted, and this the unicorn kept the suspicion to herself.

A week after, a second unicorn went missing, a strong stallion, and this was even stranger, for while the young might decide rashly and suffer bitterly for it, he was not young and headstrong any longer, and while he might have departed the vale to search for the mare that had vanished before, he should have told someone if he had.

In the search, the unicorns shied away from the stranger’s cottage, as though the place was not worth noting and not desirable to be near. Once or twice, the unicorn looked at it, and she thought it might be wise to go there, but then some other thought forced itself to grip her and she was led away from the site.

Yet when a third unicorn seemed to lose her way, the one who had first welcomed the Stranger onto their land felt it her responsibility to finally go to her abode. She ran there, and when it came into sight fought back the aversion, the nearly overwhelming desire to look anywhere else. In the end, she reached the threshold, and pushed at the door.

The portal swung open easily. There stood the stranger in a crimson dress that clung to her form like a slick covering of blood, back to the door and the Unicorn. In front of the stranger was a unicorn, laying peacefully as though asleep, but very certainly dead, horn cut from its head. In her right hand, the strange held a broad knife and in her left she held the horn of a unicorn.

“What a bother.” The stranger said with a heavy sigh, “What a bother. I hoped my spell would keep the lot of you away.” She turned around to face the Unicorn.

The unicorn projected her rage, the pain of her betrayal at the Stranger, and the stranger lifted the hand holding the severed horn gingerly to her temple.

“Yes,” she said, “You’re quite right. This is a monstrous thing, but I have no choice. Millennia are behind me – I have outlasted kingdoms, even worlds, and now I have no time.”

And this means you kill us? the unicorn demanded.

“It isn’t that I want you to die.” The stranger said, “I wish this could be done another way, but it’s the only one I’ve found.”

To do what? Though seething, the Unicorn was also curious, for she could not conceive of senseless evil.

“To live.” The Stranger replied, “If it were just for me, I might let time do its dirty work, but no… my work is too important. However much I wish you understood, I know you never can, and that much is good.”

Again, the Unicorn spoke only wordless indignation.

“Leave,” the Stranger said, “and forget what you’ve seen. Or lay yourself down and let your life stand for another of your kind. I should only need a few more.”

The words of the stranger had a strange honesty to them that gave the unicorn a moment’s pause. The waves of her anger broke, and the stranger relaxed, and smiled that same smile she had when they first met on the verge of the wood.

Without giving any warning, the Unicorn charged. In the blink of an eye, the Stranger was impaled on her horn, the blessing and weapon both of the Unicorn driven between the Stranger’s ribs, blood staining red dress and lily skin, pearly horn and white muzzle.

The Unicorn lowered her head and stepped back, and the Stranger slid backwards. There was life in her yet, but not much, and her hands released the knife and the horn. The harm had gone from her, and sorrow and horror filled her eyes.

“You don’t know what you’ve done.” The Stranger said, voice small and scared, “Look at me – I’m really dying.” One hand reached idly to her wound. “I can’t fix this. I don’t know how; lost that and so many other things when the Curse echoed from Dominaria.”

The Unicorn paced closer, wary though she could not conceive of any further harm the Stranger could do.

These things you say don’t mean anything. The unicorn said, You are mad.

“I wish I were.” The Stranger said. She reached up and placed the blood-slick tips of her fingers on the Unicorn’s muzzle, “You will understand the truth, I can do that much.”

A strange feeling hummed in the Unicorn’s mind, slowly building, but she could not pull herself away from the Stranger.

“Don’t thank me.” The Stranger said, “I dread what I give you more than death.”

And then the planes were opened to the Unicorn.

The Unicorn ran, putting the human settlement to her back. Another plane the Stranger’s curse brought her to, and more humans. Always, there were some that reacted with wonder but more with fear, anger… greed. These things the Unicorn had learned, and good fortune alike had spared her life, that and the fact that not all the numbers of humanity were always bad.

This latest place was mercifully a small town, and so when the Unicorn ran, she could disappear into the woodlot near, and there perhaps get a moment’s rest. Dominia – a word she knew in a halting, vague sense from the memories of the Stranger that dwelt deep inside her – was not a kind place for a unicorn. A shady hollow, though… it would do for a night, for the Unicorn was very tired.

When she awoke, though, there was a human sitting on one of the rocks before her. The Stranger’s memories gave her some sense of his appearance. He was young, but homely as the Stranger’s estimation would have put it, his head somewhat flat and his nose somewhat large. He wore bright blue robes embroidered with overlarge five-pointed stars and crescent moons that hung from his lanky form, and a tall, conical hat of the same cloth.

When he noticed she had awakened, the human spoke to the Unicorn.

“Hail to you, mighty Planeswalker.” He said, bowing his head, before reaching up to steady his conical hat.

I… the Unicorn thought at him, Planeswalker? You know me as such a thing?

“Oh,” the man said, “I couldn’t mistake the way you appeared for anything else.”

Then you are one too? the Unicorn asked. He did not seem to be the least threatening, and since the Stranger, the Unicorn had become far more used to recognizing who was and who wasn’t.

Excitedly, the man waved his hands in front of himself “No, oh no.” he said, “I wouldn’t pretend to that.”

Then how do you know of Planeswalkers? I have not met a human who does before?

“I was a spellsquire to one, once.” He said, “Actually, I was quite a lot of things, but that is far in the past, I fear. Tell me, Great One, what brings you to this rustic world?”

Why do you call me great? the Unicorn asked.

“Well,” the man said, “You are a Planeswalker – second only to a god, if that.”

The unicorn looked away from the man.

I am afraid you are mistaken. she said, I am just a unicorn who suffers this curse. There is no great power in me.

At this, the man looked quite distraught.

“Oh,” he said, “I’m terribly sorry. But curse, you say? What curse?”

To wander the planes of Dominia, the Unicorn replied, To be unable to go back to the home and the family I love, because I am now so different.

“How… did this come about, can I ask?”

I killed a Planeswalker. the Unicorn replied, And she passed something from herself to me that made me one. A spark – that is what she calls it in the memories that swarm within me. She… remembered that godlike power you spoke of, and a great curse that came down and stripped it away.

The unicorn hesitated.

I might be able to learn more, she said, but I do not like to dwell on those thoughts that are not mine. I do not know what they will do to me.

The man seemed to think about that for a moment, very dour and serious though his face was itself somewhat comical, even frowning.

“I imagine,” he said, “You can’t change your shape, like they once could. I can’t imagine it’s very convenient to be a Unicorn.”

It is not. the Unicorn said, But it is what I am.

“I might be able to help you.” The man said, “By the way, my name is Cornelius. What’s yours?”

The unicorn projected the thought of herself, the sense of her identity.

“That,” Cornelius said, “Is very good and something you ought to hold on to, but if you want to have an easier time, you’ll need something people can say. Would you follow me?”

The unicorn stood, and paced behind Cornelius when he started to walk.

I do not know what a good name would be, she said, Human names are a very strange idea.

“Well,” Cornelius said, then thought for some time, rubbing his clean-shaven chin as though stroking a beard, “Do you like the sound of Mari Gwynn?”

It is a fair sound, the Unicorn said, But what does it mean?

“It means ‘White Mare’.” Cornelius replied, “I mean no offense, but such as you are you have a somewhat horseish look, again meaning no offense. I don’t think anyone would take you for a horse.”

You may call me Mari Gwynn if it suits you. the Unicorn said, And meaning no offense myself, I shall say you are somewhat… strange.

“It’s the hat, isn’t it?” Cornelius said, “People always say it’s strange, or old-fashioned if they’re being generous, but I rather like it.”

The hat is fine. The unicorn – Mari Gwynn – replied, As is your manner, strange though it is.

“A strange manner? Well, I suppose I’ve had a strange life. But I hope some of that will let me help you.”

Do you think you can remove the curse? Mari Gwynn asked, hopeful.

“Alas, no.” Cornelius replied, “I’m just a prestidigitator myself, and while I might happily make an exchange of fates, or even just free you from what you suffer if I could, I can’t. I just might have something or other that will make it easier to live with.”

What about the Planeswalker, the one you knew? Could you find this Planeswalker? Would they help?

At this, Cornelius’s manner went still, losing the fidgeting and humor he had previously possessed.

“She died a long time ago.” He said.

From there, they walked in silence.

They reached a small hovel built, it seemed, into an old and mighty tree. Cornelius entered, leaving the door open, and Mari Gwynn warily trotted in behind. The interior was… cozy, something told her would the human opinion of it, but also very cluttered. On every horizontal surface, there were a variety of mementos, knick-knacks, and other unidentifiable artifacts. Mari did not enter far, for fear of disturbing some shelf or table so laden.

Cornelius, though, moved quickly between them, intensely familiar with every teetering pile’s position in space. Finally, he found something, explained wordlessly, and returned to Mari, near the door.

“This is it,” he said, holding out an amulet, “I think this little thing might help you.”

What does it do? Mari Gwynn asked

“Well,” Cornelius said, “It lets whoever wears it take a form that reflects their character inside. Now, the first time I tried it, it turned me into a dog, so Rhonwen altered the enchantment to make sure it always made somebody some variant on human. Well, there were actually a couple rounds of alterations, to prevent any embarassments.”

Rhonwen?

“The Planeswalker I… knew.” Cornelius said, “It was a gift from her, because I was so frustrated at being useless as a Spellsquire. I have my little enchantments and thaumaturgies, but nothing that could stand up to a Planeswalker, and you can probably see I wouldn’t make much of a warrior.”

You seem to hold her memory very dear. Mari Gwynn said, Are you sure you want to give such a thing to me?

“I don’t use it anymore.” Cornelius sighed, “I don’t have much cause, and I don’t really think it would be the same, after so long. So if it can help you live with the curse you bear, I’d gladly give it up.”

You are very kind.

“Not so much.” Cornelius said, “I just have a soft spot for Planeswalkers, and I suppose for lost souls. May I?” He held out the amulet, one end of its chain in each hand, and Mari Gwynn nodded assent.

Cornelius approached, and hung the amulet from her neck.

“There,” he said, “Now, you should be able to focus on it to change. It’s hard to describe, but it should feel –“

Mary Gwynn found the power Cornelius was speaking of, and in the blink of an eye, the world shimmered around her. Immediately, she was someone, something else. She felt tall, and somewhat unsteady as she realized she was standing on two bare feet, but all the same her body seemed to know how to keep its balance. Mari Gwynn looked down at herself – she was clad in a white dress, but her body looked somewhat like the Stranger’s though how much that was true and how much was simply that she was human and female she could not say. Her skin was fair, and her hair was long and as white as her coat had been.

“… natural.” Cornelius finished, “Well, I won’t say that you won’t still draw attention, though it might be of a different sort.”

Mari Gwynn tried to speak as she was used to, but found her mind was more closed. She thought she could do it, but… not like a unicorn, not quite. Perhaps after the human fashion?

“I…” she said, “I see that it worked, at least.”

Her voice, Mari reflected, was at least nothing like the Stranger’s. Perhaps they were not as similar as she first thought.

“If you think it would help you,” Cornelius said, “It’s yours.”

Mari nodded. “I thank you very much for your gift. I have some questions for you, though.”

“Oh, go ahead.” Cornelius said

“I’d like to know more about your time with Rhonwen.” She said, “If you do not mind too much speaking of it.”

“I can say a few things.” he said, “If you think it would help.”

Cornelius moved to the door and shut it, and led Mari to a comfortable chair in which she seated herself.

“I’d like to know as much about Planeswalkers as I can.”

“Well,” Cornelius said, “Rhonwen and I were friends, when we were both just human. Then her house caught on fire. I went in to try to get her out, and… well, we were on our way out when a beam fell from the ceiling. It caught my leg, but it fell on her entirely. I thought in that moment she’d been killed… but a moment later she was dragging me out, through that darkness they call the Blind Eternities.”

“Did she change then?” Mari Gwynn asked

“Not at heart,” Cornelius replied, “I hope that brings you a little comfort. Whoever you were before, that’s still who you are.”

Mari Gwynn thought very carefully about her next question. She wanted to know, but she did not want to upset her host, who had been so kind.

“And… may I ask what happened to her?”

“Another Planeswalker.” Cornelius said, “A monster like an octopus or a dragon or… I don’t know really how to describe it, though it’s burned into my mind. I do know I’m here because I was just beneath its notice. I couldn’t save her. Couldn’t even make myself enough of a nuisance to her killer to follow her. So I’m stranded here.”

Mari Gwynn thought on that. A part of her mind went deeper, into the memories of the Stranger, and plucked forth a pearl of knowledge.

“The Stranger seemed to think the Great Curse on the Planeswalkers happened nearly a century ago.” She said

“I wouldn’t know whether it did or it didn’t.” Cornelius replied.

“Cornelius…” Mari Gwynn said, “How old are you?”

“To tell the truth,” Cornelius said, “Really, very old. Older than a human ever ought to be. I’ve lost track of the exact years, but it’s in the thousands.” He sighed, “I don’t tell most people that, but I know more than enough of your secrets. That was another of Rhonwen’s gifts to me. Planeswalkers live forever, or at least that’s how it used to be, so she made sure I’d be able to be there too.”

Mari Gwynn looked away, “I see why you might know a thing or two about curses.”

“Oh,” he said, “It’s not all bad. Like your curse, a lot of people would do anything to have it.”

“I don’t know what’s fitting,” Mari Gwynn said, “But I do not wish to overstay my welcome. You have done me a very good turn, and I’m afraid I have no real way to repay you”

“I don’t really need for anything.” Corneius replied, sinking back into his own chair, “But if you’d like, if you can drop by when you’ve found some means of lifting your curse, I’d like to hear your full story.”

“That,” Mari said, “I can do. The day is young, so perhaps I should… depart, if it would not be rude.”

“Not at all,” Cornelius said, “And one last thing… If you can find your way there, the plane called Dominaria might be a good place to start looking.”

Dominaria, Mari Gwynn thought. The Stranger knew that name, the song of Dominia, bright center of the Multiverse.

It was as good as anywhere.

“Thank you, Cornelius.” She said, “If it is remotely within my power, I’ll return as you’ve asked, and bring the amulet back to you as well. After all, when that day comes, I shan’t need it any longer.”

Cornelius nodded quietly, his conical hat sliding slightly down his brow, and Mari Gwynn, in her human body, stepped back into the Blind Eternities.

Part One

"know here" - know her

Part Two

There are several places here where you are missing end punctuation

Part Three

"I couldn't save here" - save her

"bright center as the Multiverse" - of the Multiverse