The recipe for this item is taught by the Goblin Engineering Trainers.
Goblin Mortar as an ingredient
The Goblin Mortar is the only Engineering trinket that performs an AoE stun which is not removed by combat.
Reloading The Goblin Mortar gives a skill up every 3 or 4 reloads.
Patch 2.1.0 (2007-05-22): The Mortar:Reloaded no longer gives these skill increases while gray.
Attempting to reload the mortar while it still contains ammo will result in massive damage to the player, more than likely killing him/her.