This is reblog from the Halo Wiki
The Activation Index, the Key, or Sacred Icon as the Covenant call it, is an object found in every Installation’s Library. It is the key needed to activate theInstallation, causing a reaction that will purge the galaxy of all sentient life. When inserted into the Core of the Ring, the Index activates the Installation’s main weapon. It is confirmed that an Index cannot be used to activate any Halo besides the one it is found on. The reason Alpha Halo’s Index worked on the replacement ring at the Ark was because they were both Installation 04. This may be found in all of the libraries on all seven Halos.
John-117 noted in his debriefing of the Halo event that, if not for Cortana‘s intervention, he would have accidentally activated the weapon and destroyed all life in the galaxy. Halo’s main weapon exists primarily in case the Flood manage to escape containment and spread their infection to other planets. Only one firing of the rings occurred, at the close of the Forerunner-Flood War.
- “Most of the crew – not to mention your fellow jarheads – will be leaving the ship in lifeboats. They’ll ride to the surface in air conditioned comfort, sipping wine, and nibbling on appetizers. Not you, however. Oh no, you’re going to leave the Pillar of Autumn in a different method. Tell me boys and girls… how will you leave?”
- “We go feet first, sir!”
— Shock Trooper’s response.
The Orbital Drop Shock Troopers (ODST) are a special operations capable organization of the UNSC Marine Corps that specialize in orbital-dropped shock infantry and special warfare tactics. The ODSTs are one of the primary Special Operations units of the United Nations Space Command, and is under the supervision of Naval Special Warfare Command.
Starting today every Thursday I will bring you a little piece of Lore up to the launch of Halo 5. Some of it may relate to Halo 5 and some of it may not. Below is the Halo Wiki Article on Mendicant Bias
- “And so here at the end of my life, I do once again betray a former master. The path ahead is fraught with peril. But I will do all I can to keep it stable – keep you safe. I’m not so foolish to think this will absolve me of my sins. One life hardly balances billions.”
05-032 Mendicant Bias was a Metarch-class Ancilla. He was the most advanced Forerunner AI at the time of his creation, and was charged with organizing Forerunner defense against the Flood before his defection to theGravemind, who ultimately caused him to become rampant, and turn against his creators.