Halaster's blacksphere

Halaster's blacksphere, also referred to as blacksphere, was an evocation spell that enveloped an area in a sphere of force that trapped anything caught within. It was developed by the "Mad Mage" of the Undermountain, Halaster Blackcloak.

Effects
Upon casting this spell, the blacksphere appeared in an area within approximately 250' (76.2 m) of the caster. Comprised of pure force energy, the sphere appeared black as night and had a radius of 10' (3 m). Unless they successfully dodged the spell, any creature caught inside was trapped for the duration of the spell. They could only escape by any means that pierced or otherwise bypassed a wall of force.

The sphere lasted for over a minute, and extended longer depending on the skill and experience of the caster.

The newer version of this spell could only be cast by much more experienced practitioners of the Art than the older version. The newer spell did at least three times more damage than the old one.

Usage
This spell could be used in lieu of wall of force in the creation of beads of force.

History
While it was unknown for many years who formulated this spell, some scholars insisted it was called Hilather's Blacksphere. Sometime after the Year of the Banner, 1368 DR, the spell was accredited and called Halster's blacksphere. As a background, Hilather, according to Elminster, was Halaster's given name before he changed it into the grander-sounding Halaster.

Components
In addition to verbal and somatic components, this spell required a lump of charcoal and small piece of onyx.