Installation 04

The Forerunners thought they were so clever when they built this place. Ooh, they said, lets build a weapon that can wipe out all life in the galaxy, just to destroy a Tier 7 life form. And so they did, but instead of killing off all the Flood they said, hmm, these little guys are actually pretty cool, lets keep them on the weapons we used to destroy them so that they will not go extinct and are in a great defensive position against anyone who doesn't want to harm the rings...

Guilty Guilty guards this ring, and he doesn't like it when people unleash the Flood.