Dwarves have found many uses for gunpowder since they discovered it. This weapon is a warhammer with a powder reservoir, a priming chamber and a pressure trigger. When the hammer strikes a target, the trigger ignites a gunpowder charge which causes an explosion that pushes a jet of flame through a small hole in the head of the hammer.
An unloaded hammer deals damage as normal, but without the 1d6 points of fire damage. Loading a hammer is a move-equivalent action that provokes an attack of opportunity. A gunpowder load for a dwarven thunderhammer costs 1sp. Dwarves treat the dwarven thunderhammer as a martial weapon; all other races treat it as an exotic weapon.
Tome of Secrets