Shadow Weave

The Shadow Weave is a force of magic similar to the Weave. The Shadow Weave originates from Shar rather than from Mystra. Shar studied the Weave long ago, and created a dark distorted version of it, and it is said to lie in between the strands of the Weave. Though the Shadow Weave has existed for quite some time (at least several millenia ), only in recent years has its use spread rapidly and become known.

A spellcaster who wants to manipulate the Shadow Weave must either worship Shar, permanently lose a piece of his or her mind, or make some sort of arrangement with Shar and his or her existing patron deity. A Shadow Adept is a spellcaster who specializes in using the Shadow Weave.

The Shadow Weave is best suited for dark magic that drains life or muddles the mind and the senses, but less suited for magic that manipulates energy or matter. Spells from the schools of Enchantment, Illusion and Necromancy are enhanced, while those from the schools of Evocation and Transmutation are impaired. The Shadow Weave is also superior for fueling spells that create darkness (spells with the darkness descriptor), while it is impossible to use it to create light of any kind (spells with the light descriptor).

Since the Shadow Weave is a separate force of magic, it is not affected by areas of dead magic or wild magic within the Weave. An anti-magic field field however counters all magic within its area, and that includes wielders of shadow weave magic. Shadow weave users must also overcome any spell resistance a creature might have. It is harder for a Weave user to perceive, counter or dispel spells created by using the Shadow Weave, but at the same time it is also harder for a Shadow Weave user to affect spells created by using the Weave. Any magic item created using the Shadow Weave is a Shadow Weave item and affected by the same benefits and limitations as a Shadow Weave spell.

Spellplague
Just as the Weave collapsed with the death of Mystra so did the Shadow Weave. Shar had miscalculated.