Siege Weapon-making I (sage ability)
Grants material knowledge of devices designed to break or circumvent castle doors and walls, or enable attacking soldiers to scale walls and attack the defenders; and likewise, to enable defenders to prevent sieges. The ability enables the character to direct unskilled persons in the fabrication of these, so that with the necessary materials it is possible to build trebuchets, catapults, mangonels, ballistae, siege towers, battering rams, portable shields, oil smelters and like machines, including ladders and hooks. These may be made to rest upon castle walls or mounted on wheels, pushed by soldiers or dragged by animals; the amateur ability, however, only enables the character to fabricate the most familiar forms of these engines. Innovation is not permitted, nor is the creation of mystical weapons such as the Chinese cannon.
The details for these specific constructions are found in the links above. The ability grants the character with an apprentice's knowledge, but does not grant competence in managing a crew or firing accurately.
The character will have knowledge of what materials need to be collected, whether purchased or with wood and projectiles either cut or quarried from their source. The character can therefore identify certain trees or stone outcroppings.
See Also,
Fortification
Siege Weapon-making II
Sapping