There are three hundred fifty miles between Angband and Himring. Elves and half-vampires both have excellent eyesight and can see it coming at their leisure.

They throw some non-nuke-carrying planes at it, just to see if that does anything. It does seem to slow it down a little to have a plane plunge into it; each time it stays still for half an hour, swirling.

So he can order a stream of planes, as many as they have, differently enchanted in case some enchantments turn out to slow the Enemy down extra...

Elspeth'll enchant planes, although half an hour per airplane doesn't seem like a very good rate.

Nope. They only have around a hundred airplanes. But maybe it will allow them to extract the Silmarils in time.

It gets dark. The Enemy glows so hot that this is barely an impediment.

And she has to sleep. (And can't see heat, but no one was relying on her for that.)

In the morning the Enemy is still at a terribly-purchased standstill, reforming himself after another plane's flown into him. 

Maybe they could catapult rocks at him or something.

They have lots of catapults set for when he gets closer, but his scorching-things range is much bigger than conventional catapult range. They tried having some of the planes drop rocks; it didn't do much, and he usually managed to crash the planes anyway. 

Oh. Well, she's out of new ideas, then. She could enchant things if they have things for her to enchant.

No one knows the instructions that made the Silmarils in the first place, or she could try replicating them. 

By mid-afternoon a Silmaril is found. They've been holding a few planes in reserve to go and get it out. They send those off, on a route that'll keep it well away from the Enemy.

When the planes take off the Enemy starts splitting into two, down the middle, slowly and with much swirling of superhot radioactive ash.

That is concerning. Are the halves at least smaller?

...nope.

Lovely. She reaaaaally regrets the nuke at this point.

Well, they did not exactly have a way of anticipating that their Enemy would get more powerful when destroyed utterly.

The found Silmaril is brought back to the city. The surrounding countryside is evacuated. They put it at the top of a tower full of mirrors and can she do amplification enchantments?

Sure. Geez this thing is bright.

Yep. The engineers are frantically trying to figure out how to weaponize it. In the meantime it will keep the whole city blindingly bright and undecaying to a degree that should keep nuclear ash monsters out. 

That's useful.

May as well also try sending one of the remaining planes to Valinor to beg for help. No one is optimistic. Does Elspeth happen to conveniently have sourceless truth on how that's going to go?

No. She's generally not so much truthy about the future even when that feature is working.

Well, regular non-sourceless truth suggests it's going to end badly but they may as well at least try. 

Did anyone explain to Elspeth why appealing to Valinor for aid is likely to end badly?

Not as such, no.

The Valar disapproved of the behavior of the Noldor in departing Valinor and Doomed them. It was - well, it was fairly deserved, all things told.

That doesn't really explain why they're letting the evil god terrorize everyone else too.

They'd probably do something eventually. They just make up their minds very, very slowly. And they might want the Noldor to get wiped out first, to teach them a lesson.

Well, if you have that method of lesson-teaching available and can expect to have lesson-learners afterwards because you're a deity Elspeth can see how that would appeal to a certain horrible sort of person.

Did Elspeth expect that there were any non-horrible people in this whole mess?