Siege engines, which dwarven fabrication could build to the level of ballistas, mangonels, and trebuchets.
Fabrication
Dwarven artillery fabrication is at a level that could make ballistas, mangonels, and trebuchets.
Fabrication usually combines wood frames with hardcast and steel fittings.
In Markish lands
Siege warfare is uncommon in Markish lands, but some lords have a desire to have such engines built.