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“This is The Librarian's Gift? This is what we came for? Full of the Forerunner's secrets?”
Jul 'Mdama questioning after Doctor Halsey is released from the Librarian's Shrine
The Librarian's Gift

The Librarian offering the Janus Key to Doctor Halsey.

The Librarian has many gifts that she creates to propel the Forerunner and humankind.


“Reclaimer, the genesong I placed within you contains many gifts, including an immunity to the Composer, but it must be unlocked.”
— The Librarian to John-117

The Genesong is a gene that was put into John-117's DNA that contained many other abilities, the main ability is an immunity to the Composer. With it the user will not deteriorate when hit by the Composer, but will be stunned or put into a temporary lock. As the Librarian mentioned, Master Chief will not be able to defeat the Didact without the Genesong and the Genesong can only activate the abilities when it is unlocked by the Librarian herself.[1]

Janus KeyEdit

Main article: Janus Key
“We did not create so much, without a means to catalogue it all. This was meant for my husband to help your people, when his meditation was complete.”
— The Librarian to Doctor Halsey

The Janus Key is a device that is comprised one blue with orange detail and the other orange with blue detail. The Janus Key offers the real-time location of all Forerunner technology in the Milky Way Galaxy. This key, as the Librarian mentioned, was supposed to be used by the Ur-Didact to assist humanity after waking from imprisonment, since that failed to happen, she passed the key onto Catherine Halsey, hoping that she'll make humanity reclaim the Mantle, as Requiem's time was coming to an end. Upon assembling the Janus Key with both pieces, it will emit a 3 dimensional representation of the Milky Way Galaxy and within it the realtime location of every piece of Forerunner technology ever assembled, but this possibly only occurs in the Librarian's Realm. If the pieces are not together, then it is considered almost useless.[2]


  1. Halo 4, campaign level Reclaimer
  2. Halo 4 - Spartan Ops