Nightshade is a deadly plant, as such it is often described as poison nightshade.
It is often used as a spell ingredient. The berries of the plant are incredibly dangerous, as is the poison that oozes from the plant.
Alexander avoided touching the poison of a Nightshade bush on the Isle of the Sacred Mountain, he was careful that none of the poison rubbed off on him as he entered a cave.
Shamir Shamazel, in the form of an old lady, tried to trick Alexander into thinking the berries would grant the ability to fly.