Sapping tool

There should be a sapping tool which is explicitly designed to tear down fortifications in a hurry. The downside to this could be that the materials are rendered, in the process, unrecoverable, but the upside being that it would allow you to cut unique paths into enemy territory (such as Surat's rest), via an underground entry.

The Sapper's Tool should also have upgrade options like other tools, but should be available from the beginning of the game via Metal Scraps, and having improved versions available thereafter in copper, etcetera. The Sapper's Tool should do exceptional damage to structures and barriers, enough that you could bore through virtually any wall with the Sapper's Tool before it breaks and needs to be repaired.