There's an amphitheater, a place where a hundred of the stone walkways twine around to create space for a hundred thousand people to sit in close proximity, and someone is giving a lecture or a demonstration at the base of it, the seats closest to him filled with eager, tiny, bearded Dwarf-children.
And they spiral down, and down, and down, past waterfalls and egg-sized gemstones left half in the rock and halls of crystal. Everything grows gradually more ornate and more perfectly maintained and the clang of hammers fades behind them. "People say," her guide says, "that we only have a council instead of a single King because there were nine winners of the competition to design the throne so we couldn't just select one person to sit it." And they push open the doors to reveal, indeed, nine thrones so elaborate it would be hard to choose between them, and nine squat bearded people sitting them.
Bird. Debird?
"Okay. That'll make getting everybody remaining taught to fly and into the city faster. Can you sense other Maiar even if they're invisible or whatever?"
"Okay. Any obvious flaws in teaching everybody remaining here to fly right now and booking it for safety?"
"Well, that obviates the use of you being able to de-bird people so we can get through the lot of them at the gates faster. I don't require you to enter the city; you think he'd make a fuss about you being near it in a way I couldn't defuse in time?"
"By the way, this plan involves you turning into a bird too, assuming that works on Maiar, which it should as long as you're humanoid at the time. Swifts're faster than bats."
"Okay. So I'll go turn twenty five hundred people into birds and we will talk details on how close you're willing to get to the city."
And Loki rounds up literally everybody and sleepskips them all and turns half of them into birds and puts all the Elves on osanwë-teaching-to-fly duty and all the nonbird Men on bird flinging duty.