Netherese enclave

An enclave was a floating city built by the Netherese before the fall of Netheril.

They were powered by a mythallar, a massive crystal that released large amounts of raw magical energy.

The Netherese used an epic magic spell called Proctiv's move mountain, which cut the top off a mountain, flipped it over, and floated it through the air so they could build a city on the flat surface.

They then put one of these Mythallar inside of it causing it to float or fly.