It would use materials they had recently discovered underground that shows interesting properties.
The Elves had another idea wich involved making a gateway capable of transporting the MC to the desired world.
The Promethean is used to primitives denying godhood initially. It hands them the spear and javelin. The elves have no frame of reference for grenades and shouldn't suspect anything. The Promethean has exact knowledge of how to create a powerful telescope, but insists it is unnecessary. All that is needed is materials, and the MC can build up to a signal emitter to signal the fleet.
Also we would ask that you hand all of your weapons to us.
By comparing the stars they see with this telescope and the stars the MC most likely remembers from its own home the Elves will be able to triangulate the place the MC came from and formulate a method of sending it home.
A small chuckle erupt from the elf after hearing the phrase scum humans. They say that they do not believe the being is a demigod. The elves do not believe in the gods rather devoting themselves to Logic and order. But they do believe that the MC is from beyond the stars they see with their eyes alone. They will help this creature return from whence it came but first they must build an observation device from which to see the stars they have long forsaken.
The Promethean waits for each language to be spoken, and selects the one it knows best to communicate. It statest hat it is a demigod fallen from the skies and seeking to return to the heavens. It has been told by the scum humans that the elves may be able to assist.
The gates shiftbut do not open. An Ellis positioned on theater side. It is one of the few who were educated in the surface speeches and should be adept in and diplomatic proposals. The gate has a communication mechanism allowing for communication to the outside world. It ask "What do you want?" Repeatedly in different languages.
This delay results to the second action stated, of learning the langauge (as far as can be learned from the door). The Promethean waits for a maximum of 2 days before action 3 would be necessary.
An automaton has begun to descend into the eternal realm with news of this knocking. It will take time for its descent but the rest of the response will be swift. Something that would even dare consider knowckibg in their doors would obviously be a source of interest.