Just a minute.

Checking that no one else is currently looking at her...nope. Can't know no one else happens to be looking directly above, unfortunately.

The machinery assembles quickly. Even when the water's warm it's not quite comfortable, out here in the middle of always winter and they probably don't have Christmas, but it'll do. She ascends, in a human-sized water droplet surrounded by an almost decorative sheet of ice.

I'm up. Can you see me?

Nope.  Oh, wait, I can see where I assume you are. You're not the same temperature as the outside air, but it doesn't look like a person, just a spot.

Suspicious enough that they'd connect it with the mysteriously appearing messenger? I can try to adjust the temperature, up or down?

Down, but I don't know what ambient air temperature on their side of the lake is.

Good point. Probably higher than this, if they're living there on purpose.

Doubt they'll connect it to you. They probably have a lot on their plates, and I actually expect they don't look at the ocean much.

All right.

Is there a final version of what I'm telling them, or is it your line about meeting you with swords or food? Anything I should make sure not to say?

Uh, similar content, less confrontational, message is 'we are crossing the Helcaraxe. No one has died yet, which means it's not too late yet for you to set this right.'

That does sound less confrontational, but if they don't have the boats anymore it means it's going to be too late by the time there's anything they can do. That doesn't decrease the odds of them cooperating?

They definitely don't have the boats anymore, they set them on fire. I think their reaction will be valuable even if they actually can't save everyone.

I can pass it on.

And flying. Flying is the best use of, well, a lot of things.

She flies low enough and slow enough at first to get a view of the ice on the way. It's even worse than it sounded; half the time it's free-floating floes without much continent to speak of underneath. They're planning to simply walk across? Maybe some descriptions of it from the air will at least help with planning the trip.

After accelerating to speeds for crossing an ocean at, she flies east and periodically checks for lights denoting the presence of people. (Do they have an east? Oceanward. This can be east.)

There are no lights. There are the sounds of a fight going on.

Seeing infrared is one thing. But seeing only the one subset, did they just not bother? Oh well. Toward the fight, then, watching for any suddenly appearing connection marking her as having been spotted.

Is it obvious who's fighting and on which side?

Both sides are humanoid; one like the people she met on the other shore, except armored and bloodied and exhausted-looking; the others are shorter, mutilated, paler-skinned, mostly hairless.

That answers that, then. Hovering above the battlefield, the next question is now what.

Humans and presumably other humanoids contain a lot of water. Messily killing some of the Enemy's minions one by one without being spotted is...probably doable. Also really bad karma: this is technically someone else's fight no matter how justified and joining unprovoked would cost. And it would magnify the risk of someone from this camp figuring out too much.

Battles with swords and armor are not a normal thing to stumble upon! Are there people about to get stabbed and in immediate need of an opponent disappearing? At least those extreme cases would be worth it, if there's enough warning in this kind of battle.

With no lighting, it's really hard to see who might be in a position of extreme need. The Elves don't look good, but they're not about to be massacred either.

Yeah, even with light that would have been a bit of a long shot. It's not like she's from a culture where all women are brought up from a young age to be able to interpret the events in medieval-style melee combat at a glance.

On second thought, this doesn't have to be directly fatal. If it's the allied side doing the actual killing, that's at least less wrong from the spirits' point of view.
She sends down a water elemental, incorporeal, to go from one designated target to the next and blind them. 

It's not the most gruesome thing on the battlefield. It's a battlefield. But she knows exactly what she's doing to the insides of their eyeballs, and that's very far from making it more tolerable to think about.

The fighting doesn't end with anyone declaring a retreat, or anything like that; eventually the exhausted Elves just seem to run out of orcs to kill, and the orcs that remain seem to decide to pack up and go home. At which point one of the Elves apparently orders a charge and races after them.

It probably isn't worth taking on more bad karma just so the Enemy will have a handful fewer soldiers later. And at least now the boat-stealing cousins aren't in as much immediate danger as before.

She follows above the charge anyway.

The man leading it is very good with a sword, and very reckless, and now quite far out in front of his host, and there are more enemies racing at him from Angband, glowing fiery against the night.

And it's obstructed enough that he doesn't have a clear line of sight no matter how good his vision is. Unless he can see the glow from where he is, which, maybe.

Awfully convenient that the telepathy doesn't give away a direction.
You should rejoin your army. The Enemy's got reinforcements coming straight at you.

That stops him from running, at least; he whirls around, presumably looking for the source, and then stays warily in place until his army catches up with him. By then they do have a light of sight on the glowing creatures streaking at them.

It's glowing creatures? They look almost exactly like Balrogs but without the wings. This is a lot more intimidating than soldiers carrying fire. She could give updates on where they are and how many, but with the kind of vision the people here have it'd be redundant.

Is the army retreating, or is there about to be another round?

The man who was ready to charge out without his army looks disinclined to retreat. 

Okay, then.

What's really weird is that the fire monsters aren't Others. They look exactly the same to a practitioner's sight as when she briefly stops using it. Apparently this world just has those. Inconvenient, because if they were fire spirits a binding would at least be a scaled-up version of a known problem.

If the creatures happen to have eyes vulnerable to the same trick that worked on the humanoids, they can lose them.