In "World of Warcraft," DPM stands for "damage per mana." DPM is calculated by dividing the damage of a spell by the mana cost to cast it.
DPM is not to be confused with DPS, which stands for "damage per second." DPM and DPS denote spell efficiency and power, respectively, and they are typically inversely related. Therefore, a spell with a high DPM commonly suffers from a low DPS and vice versa. Despite the opposing natures of DPM and DPS, character talent specializations can be chosen to balance the two values and provide a selection of high-efficiency and high-power skills.