Ulmo suggests a location easily accessible by broomstick from where they met him but farther out to sea.

And Miranda preps the ocean end and goes out and drops it, plus a rock.

They ended up deciding it was safer to Imperius an orc than try to lure them into doing what they wanted. He levitates the other end, the size of a necklace, into place in front of a scouting party and Imperiuses the orc who picks it up. The spell won't last if he sleeps but Macalaurë has a song for that, at least for a couple days' worth.

And the orc goes home.

And the orc should head down to some part of the vast fortress which is very far from Melkor and lay the necklace down in the middle of a large dining hall there (Timothy has Felix pick the location) and keep thoughts private aside from bouncing this to an Elf who is Disillusioned on a broomstick eight miles directly above Angband -

- "set -"

"Five. Four. Three. Two. One -"

The sea opens into the fortress.

Orcs eating in the dining hall are immediately submerged under hundreds of thousands of cubic cubits of fast-moving freezing water. 

Shortly thereafter Felix thinks Miranda should summon the Silmarils.

Chimera wand.

"Accio Silmarils!"

There's a long wait. 

Then -

Gosh they're pretty!! So aggressively pretty!! Still embedded in Morgoth's crown, looks like.

She catches them. The crown is pretty heavy; she is not knocked off her feet by the grace of Felix.

She delivers them to her husband's alt.

"Thank you," he says. "Can you teleport us to the cave now -"

"Takes a few hops." Hop hop hop hop here they are.

With Minor and Finis. All three of them start talking over each other immediately. 

Elsewhere enormous clouds of poisonous smoke are issuing from the puddle that was previously Angband (and which has stopped growing; Melkor must have figured out how to disable it.)

...Bubble-head charms, anyone?

Can they do them for everyone?

Probably not.

All right, kids and injured people.

That they can do. Wandwave, wandwave, wandwave...

And everyone else can hold a wet cloth over their mouth and nose and try to filter out the poison and scuttle around guarding the building where Miranda Disapparated with the Silmarils.

Once the kids and injured are covered they can do more people.

They can set it up all orderly. 

And they can wait.

There is not immediately any other form of retaliation.

Valar are slow.

"So what do you need to make these things do more than be - really good lamps."

"Figure out what my father was doing, and then how to do it, and then write the instructions to the Silmarils - and figure out the interactions between them, that's another part I don't know much about - I wish my father weren't dead, then this would be a three-year project -"

"You don't know what he was doing because -"