Elixir of Shadow Power

Elixir of Shadow Power is a potion that provides a bonus to shadow damage for an hour.

Source
Elixir of Shadow Power is crafted by Alchemist with a skill level of 250.

The recipe is sold by Maria Lumere in Stormwind City and Algernon in Undercity.

As a quest objective

 * Bell of Dethmoora (quest)