In the Year of Blue Fire (1385 DR) the Spellplague was caused by Midnight's assassination at the hands of Cyric and Shar. This much is well-known. Unanchored by the goddess of magic, the Weave shrank and tore loose from the world like raw hide bound too tightly on a tanning rack. Fragments of the shriveled weave scattered themselves across the multiverse where they remained hidden for over a decade. At the end of the Plague Years (1395 DR) the few arcane scholars remaining discovered that residual energy from the lost fragments became bound with the material plane. Magic in these areas was more stable than the rest of the world during the remaining Plague years. Reinforcement of the Weave in around these Shards of Power only increased after the Weave itself was restored in 1479 DR. In the current day users of magic now find themselves wielding spells of greater power within range of a Shard.
The existence of Shards are closely guarded secrets, and the locations even more so. Dragons naturally gravitate to and attempt to lair at locations with Weave Shards to improve their defensive potential. Druid circles throughout the land have also discovered the benefits of creating Circles of Power on Shard sites.
Any magic performed on these points is enhanced as if the caster were a level higher than normal. In addition, spell effects with durations longer than Instantaneous will have their duration doubled if cast within range.