Should somepony observe her, her colors might seem muted, or desaturated, as she leaves her room behind to go find the evidence, find the local darkcaster’s intent.
But first, she needs to hear where the Guards spotted it; even for somepony like herself, scouring the entire city for such signs would take weeks. Especially doing it in secret, that could stretch it to months.
But here is where she has an advantage. Light magic only has general time travel spells; she can also simply look through time. Far easier- and since she knows where Shining Armor was explaining the evidence locations to Twilight earlier, it’s a simple matter to walk over and read the past before she heads out.
A Guard walks right past her, missing her completely.
Oh yes. Should somepony observe her, her colors are a bit muted. But they won’t be able to see her in the first place. She watches him pass, suppresses a shudder, and continues on her way. It’s been a long time since she last shadow walked, let alone around other ponies.
It takes her only ten minutes or so to reach the room they’d been discussing in. Her friends would love to know the castle as well as she does. As a matter of fact, she’s willing to bet even Princess Cadence would!
It takes her all of two minutes to listen to Twilight and Shining’s entire past exchange. Mostly because she skimmed the parts she wasn’t looking for.
Then she heads outside, still covered in her shadow-walk, and heads out into the town. Somewhere along the way, she releases the shadow walk, her colors returning to normal, and switches to a more Light-based invisibility spell. This one shouldn’t stand out to a fellow shadowcaster like the shadow walk will- and, unless they’re looking for it, they won’t even know she was there. Much like Light casters against the shadow walk.
With her colors now seeming extra bright and oversaturated to any that might observe her, she trots off for the first of the locations the magic had been detected at. She has an investigation to perform.
She returns effectively empty-hooved. The signatures she’d found were generic manipulation magics, like levitation, used on various objects. She’d timescanned a couple of them, and seen nothing dangerous. As a matter of fact, she hadn’t even seen the spell in the scan- dark magic has a tendency of not appearing in timescans. Still, all she’d seen was a few market transactions, none of which looked suspicious to her.
She lets out a sigh as she flops down on her bed. She’ll pass off her tiredness tomorrow as having missed all her ‘naps’ on the day prior. She can’t tell them the truth. Yet.
“Okay then,” Twilight states, at the breakfast table. “Here’s the plan. We don’t want this to look like anything is going on, so for the first day, we’re just going to explore the town- as a party. Me and Rarity will be watching for any additional traces- and checking out the ones we’ll pass on our way. I’ve got our entire route planned.
“For tomorrow, we’ll split up into teams of two, with a Unicorn guard attached to each team. We’ll then perform a similar sweep- but of some of the smaller areas of the town, wherever we find the most clues during day one. The parties- me and Applejack, Rarity and Pinkie, Rainbow and Fluttershy- will each go on a different route… I’ll have to plan those tonight.
“On day three, we’ll pick whichever part carried the most clues on day two and search the area alone, save a Unicorn guard with each of us. I’ll have to plan those routes tomorrow night.
“Day four and beyond depend on what we find on day three.” She draws to a close.
Rainbow suppresses a sigh. She’d been afraid of this; Twilight’s overthinking, and lack of training/experience, is going to create a situation in which they’re all vulnerable after their enemy has enough time to figure out what’s going on, rather than before. It’d make more sense to her to simply explore- as singletons with undercover Unicorn guards to accompany- until they find clues… then “explore” closer into that area.
Not that a unicorn would actually stand much of a chance against a skilled or powerful shadowcaster.
Yet she, being both skilled and very, very powerful, could completely ignore the attacks of a more run-of-the-mill shadowcaster. Her natural wards would deflect it without any effort on her part.
Fortunately, if somepony does get cursed, her power should be more than enough to fix anything shy of death itself. Even ‘permanent’ curses; she’s strong enough to dispel them anyways, so long as she wasn’t the original caster.
Unfortunately, performing any such repairs will require her to reveal herself as who she is.
They head out.
They find nothing new.
Three days have passed. Twilight’s method has, rather predictably, not turned up anything. More importantly, her crazy search has driven off any chance she might have had at locating their target during the night. Or even of discerning a purpose; no fresh spell traces can be found anywhere in town. Not even her own, from last night at least- she hadn’t gone out, electing instead to get her rest.
She zips across precisely thirteen rooftops, makes a perfect ninety-degree angle, crosses three more, and slams to the ground in the alleyway, glancing conspiratorially at either end for a second. She’s started playing games with the Guard trying to follow her- he can’t fly and, he hasn’t figured out yet, his magic is useless against her.
Then she feels a surge of dark magic nearby… But it’s not a simple spell trace, or even a spell. No. This…
She spots her target, dead ahead. This was a quick shadow-walk from that alley and a little blanket spell so nopony would notice the pony emerging from their shadow walk.
This blanket spell, of course, has no effect on her. But a shadowcaster is invisible to another shadowcaster if they don’t actually use their power; she is safe from detection.
The unicorn steps forwards, looking at her. “Something wrong?” She asks.
Rainbow looks up at her, having pretended not to have noticed her appearance- like a regular pegasus might. “Huh? Well, Twilight seems to think so.” She rolls her eyes.
“Oh? What is it?”
“Some kind of dangerous unicorn, I think. She’s only dragged the rest of us along for the Elements of Harmony… yet she’s insisting we help with the search.” She glances behind them; they’ve started walking down the street. “I’ve taken to playing games with the Guard trying to keep me safe.”
She snorts. “The Royal Guard, keep an Element of Harmony safe from a dangerous unicorn?” She lets out a sigh. “Please tell me he’s a unicorn as well.”
Nod. “He is. He’s pretty slow, though- I made it past thirteen houses before he seemed to realize I was gone.”
“Oh?”
Nod. “That’s when I turned.”
“Nice. She didn’t say anything about this dangerous unicorn, did she?”
She shrugs. “Just a little. Something about Sombra’s daughter, I think.”
“Sombra’s-?” She actually breaks out laughing. “She hasn’t asked anypony here about the aforementioned daughter, has she?”
Shrug. “Why?”
“It’s common knowledge in the Crystal Empire right now- just like it was a thousand years ago, before we were frozen in time- that Sombra’s daughter was not a unicorn, but a pegasus.” She chuckles. “A pegasus that ran away, as a matter of fact, while she was still young. I understand he vowed to punish her until her hooves fell off for that.” A sigh, looking towards the ground. “But she died out in the snow someplace. Nopony knows where; her body was never found. … What?” She’d finally looked back up at Rainbow.
Rainbow is, of course, feigning complete and total surprise at learning Sombra’s daughter’s race. She’s actually unsurprised by any of it; she knows the common knowledge part to be true, and the rest would have been easy to acquire since. It’s not like the regular Equestrian newspapers and texts that have worked their way up here in the short time since the Empire reappeared have been held under lock and key.
“She’s a pegasus?” she asks.
The unicorn nods. “Yep. And dead. I wonder why … what’s-her-name is having you search for a dead pony?”
“Twilight,” Rainbow supplies, to a nod, as they reach a nice little cafe, and seat themselves at one of the outdoor tables. “And that’d be because Princess Celestia told her to.”
“Princess Celestia…? Oh, she’s the head Princess of Equestria, isn’t she?”
She scowls. “Princess Luna is right up there with her… But yes, I suppose.”
“Princess Luna… Ahh, yes. Sorry, I’m just a lot more familiar with Princess- what was it, Mi Armoire Cadena? Hmm...” She scowls, and shakes her head slightly in thought.
“Mi Amore Cadenza, or Cadence for short,” Rainbow recites. “She married Twilight’s brother, Prince Shining Armor.”
“Ahh, yes. That’s the one I have no trouble remembering.” She smiles. “That and Sombra, but he is no more… Right?”
She nods. “As near as anypony can tell, he was killed when the Crystal Heart did its thing.”
“Right. Um… Do you know why Princess, um, Celestia, told her to?”
She racks her memory… or at least, gives the impression of such; she actually remembers it quite clearly, as is the nature of the mind of a shadowcaster, but her facade wouldn’t survive that kind of memory. “Um… I think Princess Luna said something about a night guard and a spell trace that wasn’t Sombra’s.”
“A spell trace that wasn’t Sombra’s… Like, a dark magic spell trace?” She seems suddenly worried.
Shrug. “I donno, you’d have to ask Twilight.”
She seems to wince. “If there’s a darkcaster running around, I’d rather not paint a target on my back by getting too close to the one that made Sombra’s defeat possible. Think you could ask for me?”
She tilts her head. “She probably won’t be too willing,” she states.
A sigh. “I figured as much. If… If she doesn’t want you to tell me… Perhaps this can help convince her.” She uses her unicorn magic to pull parchment and quill out of her saddlebag- Rainbow notices some minor darkcasting in use, to pull it instead from a pocket in space- and lays the blank page out on the table in front of her. She starts scribbling on the page as she continues speaking. “I’ve spotted four residual dark magic spell traces in the marketplace, dated after Sombra’s defeat. Something you may have noticed- erm, you might not have, being a pegasus, but she might have- is that each of them bears a different signature. I’m staining this page with my signature- and she should be able to tell it doesn’t match any of the traces.”
She finishes scribbling on the page, rolls it up, ties it, and offers it to Rainbow. “If that’s not enough, I don’t know what is.”
As Rainbow takes the scroll, she feels the magic signature stamped into it. Sure enough, it matches the mare in front of her- and doesn’t match any of the three traces she’d spotted in the marketplace… Which, now that she thinks back to them, were unique. “So… If she says yes, how will I find you again?”
She shrugs. “Say my name three times fast, anywhere outside the Crystal Castle, and I’ll come running… Though, I would prefer you find someplace discreet to do that, like here.”
“Ahh… Your name is?”
“What-? Oh…” She face-hooves. “Pointed Gold. Sorry about that.”
“Why would it only work outside the Castle?”
She shrugs. “Difficulty getting into the Castle aside, it’s easier to hide the blanket spell matrix that makes it work in the clutter of the town’s magic use. If I were to push it into the Castle, somepony would notice.”
“Ahh… Okay.” She stows the scroll in the saddlebag Twilight insisted she carry with her, and glances back towards her landing site. “He’s probably going to get here soon. I’ll see you around, then!”
Pointed Gold nods. “Until next time!” She then vanishes in a Light magic teleport.
Rainbow evicts herself from the cafe, checking both ways up the street before trotting back the way they’d come.
Then she pauses, looking at one of the houses she’d flown over.
Close to fifteen seconds passes before the Guard finally gallops through the gap between it and the next house, looking terribly frightened.
“Rainbow!” he yelps. “Run! They’re here!” He points a hoof briefly back at the alley. “Run!”
She obeys, after glancing up at- and feeling- the dark spell traces in that alleyway. The… less-than-friendly spell traces. With no ponies anywhere nearby, but they feel brand-new. She takes off running- and makes sure not to go so fast he can’t follow. She picks a route such that the dark spellwork effecting him- she can sense it- will wear off before they reach the castle… or cross paths with another Guard. Rather helps that she can sense them.
He seems worried about not running into another Guard on her route until they reach the castle- but when they reach the castle and he requests the check for dark magic curses, one of the other Unicorn guards confirms the presence of residual traces- but the lack of any active curse… or effect from one. The other Unicorn guard at the door scans Rainbow- and, rather predictably she thinks, doesn’t find anything. After all, any dark magic used on her is simply absorbed- leaving no trace, or effect, whatsoever. Such is the nature of shadowcasting on a shadowcaster that’s an order of magnitude- or more- stronger: She’s completely immune to their spellwork… and only experiences the effect if she wants to. Even then, only for as long as she wants to.
She lets out a sigh and, at the Guards’ insistence, waits inside the castle for her friends’ return.