- last post: 01.01.0001 12:00 AM PDT
It would be some sort of pulse, not an actual blast. Like ultraviolet-rays, it has a blast radious, and a range, but that just means how far and where the beams would travel. And like what some guy said before, it kills everything not on the Halo, the flood would therefore be unable to spread.
Admittedly, it is an odd logic, killing life in order to preserve it. But the Forerunners are most likely on a higher level of thinking than us, and their logic would seem incomprehensable to us. And since the ring has a range, perhaps life beyond that range would survive. The forerunners in this instance, are saving all sentient life in existence, by sacrificing a universe-worth of it. Again, advanced level of thinking, a higher form of being.