The disruption to the Weave caused by this ritual reacts violently to users of Silver fire, causing them to be hurt badly for every moment they spend within the ritual's radius.
The closer you get to the source of the ritual, the worse its effects become, with the worst being a dead-magic zone that allows the Shadow Weave to still function.
It has only been recorded as being used once. In the second battle for Shadowdale between the Army of Darkhope and Shadowdale's defenders, Sharran allies of the Zhentarim began the ritual which sealed the defenders' fate. Without full access to the Weave, the defenders were even more easily outmatched. Adventurers disrupted the ritual and Syluné Silverhand expended all of her energies to reverse the process, destroying herself as a result.