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Great Ghost Dance from Shadowrun Sourcebook, Sixth World Almanac.png

The Great Ghost Dance was a powerful magic ritual, led by Daniel Howling Coyote, used by the NAN in the Ghost Dance War to cause Mts. Hood, Rainier, St. Helens, and Adams to erupt simultaneously, the magical equivalent of nuclear war. It occurred on Aug 17, 2017, at 10:32 AM PST. After the Great Ghost Dance, the United States admitted defeat and drew up the Treaty of Denver.

The mana spike at the site of the Great Ghost Dance was later used by Darke to create a bridge in astral space to the metaplane where the Horrors reside.