Wars of Beleriand
As a magical skill, Shadow represents the ability to manipulate people, circumstance, and the environment towards destructive ends. Often associated with death, evil, and hardship, wielders of Shadow often employ treachery, deceit, hate, and vice.
Most of those few can use the forces of Shadow at all are limited to subtle uses such as causing someone to lash out in anger, give in to temptation, or more readily believe a lie. Those who truly master it, however, demonstrate more overt and powerful effects such as wielding the weather as if it were a weapon, causing the earth to tremble and vomit forth fire and ash, and seed despair in the hearts of an entire nation.