Assault drones are available as an upgrade to the assault galleon, and give them an attack similar to the protosscarrier. These swarm enemies and will rebuild automatically upon being destroyed, but the bay itself costs minerals and supply to create.
Install Drone Hanger
Retrofits the Assault Galleon with a Drone Hangar bay that automatically builds and deploys assault drones.
Assault Drones can attack ground and air units.
Endurance Training: after install Drone Hangar, Assault Galleon gain the Endurance Training ability.
Assault galleon start with 6 assault drones (maximum 6). Launch 1 assault drone every 0.25 seconds with a range 10.