Ok I will link a feat thread but it's very long so to give you the gist of it. They can build A Dyson's sphere two astronomical units wide with a minor amount of their industrial capacity. Basically even with lowball calcs this puts the feat about a death star every four minutes. Generate enough energy to alter the galactic axis. Travel tens of millions to billions of times the speed of light. As well as posses real space acceleration in the hundreds to 10s of thousands of gs. Can warp time and space on a galactic scale. Etc. https://forums.spacebattles.com/threads/forerunner-feat-thread.236388/