In the Covert Ops mission Fullmetal, some buildings in the map will be automatically destroyed and the Scorpion Cell enemies will create Bloatick Tunnels on the position of these buildings.
In Insomnia, a single Bloatick Tunnel is present near a tower by the Scorpion Cell Construction Yard. But it plays no role in this mission.
In Neuromancers, destruction of all Bloatick Tunnels is mandatory to complete the mission.
In the Contagion Challenge, there are a large number of Bloatick Tunnels that continually pump out poison clouds which cannot be destroyed and will deal constant damage to all units and buildings of the challengers.