The Bombard Tower is not an upgrade of the regular towers, but rather a seperate building that must be unlocked with Alchemy. It is a deadly merge of gunpowder and defense: it has the highest attack of any gunpowder unit AND any defensive structure in the game, and is able to kill most units with a single cannonball. It carries an attack bonus versus ships and lancers.
Armor/Pierce Armor: 3/8
Special: +40 vs. ships and lancers.