With the Blast Furnace built, the Foehn commander can begin expanding the network of Blast Trenches around his base in order to create the foundations for a steam barrier known as the "Blasticade". The Blast Trench is built in a fashion similar to the standard walls and once the Furnace's superweapon is activated will become impassable for ground units and will destroy and aircraft that tries to fly over it. If there are any objects during the Blasticade's activation, those will be destroyed as well. For the duration of the superweapon, the Blast Trench becomes completely invulnerable.
In order for the Blasticade superweapon to work, Blast Trenches are required to be constructed. Although this would mean that the the Blasticade is the only support superweapon that requires 2 elements to function, the Blasticade's area of influence can be expanded; unlike other superweapons that have a fixed area-of-effect that cannot be changed, the Blasticade can surround an entire base if the Foehn commander surrounds said base with Blast Trenches.
When the Blasticade is inactive, the Blast Trench functions as a regular wall, but all units regardless of allegiance can pass through it. However, it can serve as a distraction for computer opponents, as they treat the Blast Trench as a stationary defense, so they will it attack it until it is destroyed.
Once the Blasticade is active, no units can pass through it (except epic units). Also, most units that are standing on the active Blast Trench will be instantly destroyed. Not even aerial or subterranean units can breach a Blasticade, so a Foehn commander should plan and place these trenches accordingly.
Other than the outer perimeter of a Foehn base, the best locations for Blast Trenches are technology enhancers (like the Cloud Piercer), the Construction Yard and the Tempest Architect. Ideally, adding Bastion Walls between the Blast Trenches and the buildings they protect offer a durable blockade, even if the Blasticade is offline. The commander does not need to connect the trenches to the Blast Furnace itself.
- Blast Trenches appear in the Firestorm Challenge as one of its prime features. The Blast Trenches do not need a Blast Furnace for the Blasticade to become operational.
- The Blast Trench is functionally similar to the Firestorm Wall Section in Tiberian Sun and Firestorm.