War for the Multiverse

The Creators made the gods to gouvern over the multiverse they had created. For this purpose Curse created 1 god to manage his private planet Arkesh. During the War for the Multiverse Mystra (former) rose up against Curse.
The weave shattered all around Arkesh. To the humanoid populace on the planet it was devastating, nearly killing them all. Many of them became altered and ended up becoming The Broken .
Mystra ended up winning the conflict. But Curse being the one that shaped the god knew their strengths and weaknesses. In his death he unleashed the curse where he had gotten his name from. And in doing so damaged the god to incredible extent.