Blaze a trail
The Forerunner is a heavy command ship.
Predating Carriers, these vessels served the Xel'Naga and Protoss in joint operations colonizing and defending various worlds in the Koprulu Sector. Though not as powerful as Worldships, Forerunners easily wiped out most species attempting to threaten the two races. When the Xel'Naga decided to leave, the ships were disabled or destroyed while the Protoss developed their own interstellar craft. The remaining ships were located on remote planets by the Vaul.
In order to face the dominant races, Forerunners had to be upgraded with much more powerful weapons such as an enhanced version of Interceptors. These new variants, designated as Strikers, utilize three psionic blade mounts, robust shielding, and chrono boost technology for melee attacks. Inspired by the Zerg Scourge-strain, these incredibly fast drones can chase down targets and overwhelm them with numbers (Star Trek - Beyond: Swarm ship). No amount of shields and armor can stop them. However, the drones will self-destruct if their command ship is destroyed.
For planetary bombardment operations, the Forerunner uses a much older and powerful version of a Purification beam leaving a volcanic wasteland where no creep or psi-field can be used. No plasma shielding can withstand this beam for more than a nanosecond. To prevent the power of the beam from destroying the vessel, specialized shielding is focused on the hull (Starcraft II - Development: Tempest). This shielding has an added bonus of making Forerunners invulnerable to ground-based attacks, but leaves them open to air assaults. As such, escort vessels are often nearby to prevent enemies from stopping the Purification process.
- Build Striker (autocast) - constructs up to 10 Strikers (each dealing 30 damage). Robotic drones attack air and ground targets at melee distance and dodge all non-explosive damage weapons. Strikers self-destruct if Forerunner that builds them is destroyed
- Purification Beam - unit switches to a beam attack dealing 55 damage per second to ground targets leaving the ground volcanic and usable for creep or psi-fields. Forerunner gains special shields preventing damage from all ground-based attacks, but disables shields for air-based weapons