The Forerunners enters Starcraft galaxy at their most powerful and see The Terrans, Zerg and Protoss. They get extremely disgusted by the lack of the respect for life from the three species deifying their belif in the Manttle. Then they decide to wipe out them all.
The Creators, The Holy ones ones, The Ancients.
-The Forerunners has all their military before the Flood War.
-The most advanced shit they had. Basically, the Mega Forerunner soldiers used against the Flood.
-Morals off. Blood-lust on.
- Their technology and military power during their wars. Or, during the time of Starcraft 2 and Starcraft 1.