Mortar

Mortars are a type of siege weapon. Mortars launch a grenadelike weapon such as an explosive shell in a high orc to land near or on a target.

Background
They were used extensively as siege weapons by the Alliance during the Third War. Mortars are used by the Dwarven armies of Khaz Modan as a mobile form of artillery, when cannons simply cannot be rolled in. Dwarven Mortar teams consist of a carrier/gunner and a spotter/loader. They are well known for their battlecry, "MORTAR COMBAT!" (a reference to the video game Mortal Kombat), and their advice to targets within earshot: "Hey, you! Catch!" From the time the dwarves first learned to use mortars to the present day, there have been only 3 reported cases of the enemy being stupid enough to actually try catching the shell, with a successful catch being made only once. The name of the individual who performed this impressive feat has been lost, along with most of his anatomy and all insect and plant life in a 15-foot radius of the place where he was standing.

In World of Warcraft
It is an explosive weapon only Engineers can use or craft that produces a Ground Targeted Area of Effect. When mortars are used, a green targetting symbol appears on the ground that can be moved around. The targetting symbol becomes a red 'no' symbol when moved out of range. After acquiring a valid target, click to fire the mortar. The table below summarizes the variety of mortars available to Engineers; skill required and effects.