Organ gun

Organ Gun is a Dwarfs siege engine unit in Total War: Warhammer. Should the enemy get too close, an Organ Gun can decimate entire ranks with a well timed blast.

Description
An invention of the Dwarf Engineers' Guild, the four-barrelled Organ Gun is so called because its arrays of barrels resembles the pipes of a musical organ. The Organ Gun's barrels are smaller and lighter than an ordinary cannon's, which means it lacks that extreme range and hitting power, but has the advantage of firing a barrage of shots all at the same time. With a well-placed salvo, and all its barrels firing to maximum effect, an Organ Gun has been known to blow away entire enemy units at a time.

Strategy
The Organ Gun is the crown jewel of Dwarfen artillery technology. Its four barrels are smaller and fire lighter shot than the Cannon, meaning it loses a fairly considerable amount of range--though still much longer-armed than any missile infantry, Organ Guns cannot reasonably counterbattery enemy artillery. However, the Organ Gun makes up for this disadvantage by being able to fire multiple shots at the enemy, able to literally tear apart an entire regiment of soldiers should the crew get within adequate range of the enemy. It can perform respectably against armored troops and is easily the best of the four at fighting cavalry (though it should under no circumstances be placed where cavalry can charge into melee with the crew), and provides the Dwarfs with the field-sweeping hammer to match the impenetrable anvil of their heavy infantry.

The Organ Gun requires considerable investment to unlock, being available only to size 4 and 5 Dwarfholds, requiring two expensive buildings, and costing a fair bit both to recruit and run itself. This price tag is well worth it, however--there is almost no problem that a battery of Organ Guns cannot solve. Aiming straight for them from the start is not unreasonable, and every army should aim to have at least one unit as soon as it is feasible to do so. The time needed to build the population for a level 4 hold means that no matter what, however, Organ Guns will take a while to get out.

Organ Guns work best when paired with a typically infantry-heavy Dwarfen army, acting as the hammer to the infantry's anvil. They should be kept at the back of their army and on as high ground as possible, as their firing arcs are quite flat, making it highly difficult for them to shoot over their own troops' heads without a height advantage. They have considerable magic resistance and decent armor, so enemy ranged units are not a concern--as with all artillery, however, cavalry and flying units should be kept well away from them. Organ Guns can technically work just fine as the only artillery you field, but work better when paired with Cannons. If facing an enemy that likes to drown you in infantry (or undead), consider bringing a Flame Cannon along to clear out the chaff while the Organ Guns focus on higher-value targets.

Organ Guns should focus on whatever seems to be the biggest threat to the overall army, though single large targets may be better handled by your classical Cannons. The one place where they do struggle is against swarms of low-armor infantry, as without the armor-piercing bonus even their considerable rate of fire can struggle to put the enemy down fast enough. In this situation, focus them on enemy troops with armor-piercing to limit the damage done to your own infantry line.