"

During a demonstrational siege of Adams' test fortress, goblin invaders—now supplemented by monstrous war mounts, a scattering of beastly reinforcements, and a demonic commander—brought battering rams for smashing in fortress gates. And marching alongside them were trolls with pickaxes and building materials, acting as siege engineers who can destroy player-built fortifications and build their own floors and stairs for crossing the obstacles that might stall their advance. They'll follow new behaviors, with some units hanging back while others charge and even learning to avoid areas that have proven dangerous for their presumably-mangled comrades. Most terrifying of all, Adams said that 'if it comes down to it, they can dig slowly underground through natural walls.'