Based on the final stage from Fire Emblem: Mystery of the Emblem and New Mystery of the Emblem: Heroes of Light and Shadow it's the Dragon's Altar!
This was once where the Divine Dragon, Naga, sealed the evil Earth Dragons; but it now serves as the place for the resurrection of the leader of Earth Dragons, Medeus, who was defeated by Marth in Shadow Dragon. This time, however, he has come back as a even stronger Dark Dragon!
Fighting takes place on the large stairs and stair railings, creating a simple stage about the size of Battlefield. I'd think of it as Shadow Moses with the Towers (railings) being only 1/6 as tall. With a WAY less hazardous Spear Pillar mixed in.
Most of the stage's uniqueness is taken from its dark atmosphere and ancient ruins. It also has Flying Dragons flying around the top of the stage.
The lighting from this stage comes from the glowing torches on the pillars, the evil looking skulls, and eyes of the Dark Dragon himself!
Do to being not at full strength yet, he occasionally summons his army of Earth Dragons (the brown ones) to attack Players.
When an Earth Dragon is to appear, Medeus's eyes flash, the stage will rumble and dragon skulls in the background will glow and come back to life. Once they have appeared, they will use the dragon breath to attack for high knockback and damage. They disappear when the stage lights up and are forced back.
In the background you also see the 3 Princesses (Nyna, Maria, and Marth's sister Elice) and the Priestess (Lena) standing next to Medeus becuase his minions have captured them. But they are in a deep hypnosis, so they don't do anything besides being eye candy.
Stage example:
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Stage Name: Dragon's Altar
Stage Icon: Falchion
Fire Emblem: Mystery of the Emblem -
Dark Emperor (Hardin's Theme)
Fire Emblem: Mystery of the Emblem -
War of Heroes
Fire Emblem: Mystery of the Emblem -
Divine Child, White Sage (Tiki & Gotoh's Theme Medley)
Fire Emblem: Genealogy of the Holy War -
Final Chapter - The Final Holy War
Fire Emblem Gaiden -
A Desperate Assault - Final Chapter Theme
Fire Emblem: Shadow Dragon & the Blade of Light -
The Chosen Ones - Final Chapter Theme (Brawl Lost Tracks)
Fire Emblem: Shadow Dragon & the Blade of Light -
Shadow Dragon Medley (Brawl)
Fossil Fighters -
King Dynal
Drill Dozer -
Skullker Factory
Tingle's Rosy Rupeeland -
Deku Temple