The Calamity is the name of a wave of black magic in Spyro: Shadow Legacy. It was sent from the Shadow Amplifier machines that trapped the inhabitants of the Dragon Realms, Avalar, and the Forgotten Worlds in the Shadow Realm and drained them of most of their magic.
The Sorcerer attempted to build a second machine that would cause a more powerful Calamity to trap the world in the Shadow Realm permanently, but he was stopped by Spyro.