Firestorm, was undergoing a crisis of faith when he was taken to a land of African gods called Ifé (called the "Living Land"). Ifé was imperilled by shadows which threatened to overtake the land, creating shadow copies of everything, and everyone they touched. Firestorm himself was overcome by the shadows. Although he quickly emerged, the shadows spat out a shadow copy of Firestorm, which eventually took the name of "Shadowstorm" for himself.
Shadowstorm was a clone created from darkness and anger. He considered it a denial of his very being to be anything other than Firestorm’s enemy. A later fight between Shadowstorm and Captain Atom supposedly caused a darker side of Ayom to come to life.
The storyline might be a precursor to a darker counterpart of Captain Atom coming to life as Monarch.
Powers & Abilities: Shadowstorm is an exact clone of Firestorm so he has all of his powers. That includes heat generation, transmutation, molecular manipulation, etc