Bright and deadly ring

Bright and deadly ring was either an arcane evocation spell or psionic metacreativity power developed by the amethyst dragon Eldenser, the Worm Who Hides in Blades, to protect himself, the swords he occupied, and their wielders.

Effects
As the name described, the spell created a glowing blue-white ring of energy, similar to faerie fire, centered on a selected focal point. This focal point had to be a single solid object or willing creature, such as a door, column, sword, person, or even the caster or manifester themself, anywhere up to  for the psionic or  for the arcane, or more. If cast on an unwilling creature or one hostile to the caster, the spell failed and the ring broke into harmless motes of light that faded away. The ring was horizontal and had a radius of some in the psionic case or of any size in the arcane case. It moved with the focal point, was not blocked by a target creature's limbs or solid objects and did not disrupt actions or abilities.

At its most basic, the bright and deadly ring emitted light comparable to a candle and bright enough for one to see their way, read text, and perform fine tasks.

However, its primary purpose was an aggressive form of defense, by emitting glowing blue-white pulses of force much like magic missiles, unerring and inescapable. In the arcane version, when the caster (not a focal creature) willed, the bright and deadly ring produced a number of these pulses according to the power of the caster. In the next minute, it produced one less, and so on, until it ran out. The caster could choose to produce none, but the number still decreased and they could not be saved or held in reserve. They were silent and struck and any selected foes in bursts of light. Furthermore, any foes who crossed or touched the ring could be either allowed to pass harmlessly or struck with all remaining energy in one blast, ending the spell.

The psionic version only functioned when foes crossed or touched the ring. The manifester could either unleash the energy in a staggered manner, in amounts of their choosing until it was drained, or unleash it completely in one blast, ending the spell.

The arcane version lasted indefinitely until discharged or dismissed, remaining even while the caster was unconscious, asleep, or casting other spells, and faded away safely if they died and departed the plane it had first been cast on. The psionic version lasted a number of minutes or until discharged or dismissed.

Components & Displays
The arcane spell version required only a verbal component.

The psionic power version produced both auditory and visual displays.

Known Users
The only known user of bright and deadly ring was Eldenser, who employed it as a defensive barrier around those who wielded the swords he occupied and their companions.

History
Eldenser once taught Khelben Arunsun bright and deadly ring, just not there, and steelsteal in exchange for other magic.

Eldenser's rival dragons, Red Wizards of Thay, and the Cult of the Dragon all coveted these spells in the mid-to-late 14 century DR.