Nolofinwë answers. No. 

It gets in your lungs and does really nasty stuff to you. I don't know that any of it's fatal quickly enough to matter on a battlefield, but I don't know that it isn't, either. She focuses on trying to clean ash out of the air. Anyone who's got even a little of my magic should try to get it out of the air, and I'd recommend putting cloth over your noses and mouths if you can.

And people come around distributing cloths.

Hopefully that will be enough that no one dies of this.

Fingon's host does not encounter any resistance until they reach the edge of the dense rolling clouds of smoke and ash, and then thousands of orcs and a few Balrogs come pouring out. There's fighting. With her new eyes she can see it from the window.

She has very little talent for conquest and these things are presumably highly magic. She doesn't bother trying to directly order them to die, though she's tempted. Will the "several gees of pressure on the brain" trick work on Balrogs?

Her magic can't identify a brain on a Balrog. 

Damn. Okay, can she bisect them?

That she can do. When she does, it explodes. The Elves and orcs nearby alike are enveloped in a fireball. The ones slightly farther away go flying.

Shit. She tries simultaneously bisecting one and holding up a sort of blast shield in front of adjacent elves.

That one declines to be bisected. Must require more concentration.

Fuck. She bisects it anyway. Once the explosion exists can she redirect it so it hits orcs harder and elves less, since she's anticipating it?

That she can do, and now Elves and orcs alike are backing away from Balrogs since it seems like they might spontaneously detonate.

What a clever observation! They can continue to to that. Ow. Ow, it hurts, but oh, it's worth it. Die, you fucking monsters. Die and have your lethal explosions redirected towards your own forces, die die die die die.

That makes dispatching the orcs fairly straightforward, and a minute later Fingon plunges his people back into Dorthonion and they vanish from sight.

Adrenaline is a marvelous thing. She's probably going to fall over twitching when there aren't any more balrogs or other nasties in sight to kill and she comes down off of it, but she holds up just fine until then.

And then there's nothing visible from here but ash, though Fingon is still osanwë-reporting conditions as he goes.

Aaaand she overextended herself, yep. Ow. Ow. Ow. She slides to the floor hissing.

An attendant is there a minute later. "Do you need medical attention, or just hot compresses and tea?"

"Medical attention won't do any good, there's nothing physically wrong with me--hot compresses and tea would be amazing."

And they are brought, very very quickly. The attendant stays in the room anyway, nervously. "Anything else?"

"I need to be kept updated on anything useful I can do whether it hurts or not. But besides that, no."

She nods. "All right."

So she presses hot compresses to various aching muscles and sips tea and listens to Fingon's battlefield updates.

After a while they go quiet.