A Mythallar was a Netherese device that allowed access to vast amounts of raw magic.
This magical device looked much like a crystal ball but was about 150 feet in diameter. The globe shed a very bright light—similar to the disc of the sun—with dimmer shadows and shapes moving across its surface. An ornate stand kept the perfectly spherical device in place.
Created in 845 NY (-2934 DR) by Ioulaum, the mythallars allowed arcanists to create quasimagical items without draining their lifeforce. This allowed for a rising trade with the middle class. The first large scale application, the floating city, appeared in the year 866 NY (-2954 DR), Ioulaum’s Enclave, named Xinleal. By 1048 NY, 13 had been constructed. By 1652 NY, Netheril began lifting one enclave into the sky per year.
Its function was a simple one—it converted raw magic from the Weave and sent that power throughout an enclave to provide the magical energies required for the continued operation of quasimagical items. Every enclave contained at least one mythallar-especially since the mythallar was absolutely necessary to keep the city afloat.
The mythallar had an effective range of one mile. Therefore, if an enclave was larger than one mile in diameter, it had to have more than one mythallar.
When a quasimagical device was within the effect of the mythallar, it gained the ability to use the magical powers that had been imbued into it. Outside the area‚ quasimagical devices ceased to function as magical devices.
Touching a mythallar was a lethal decision. Anyone who touched the device was instantly slain. Any item that touched it, except the stand that contained it, was instantly disintegrated. Any undead that touched the mythallar were destroyed.