Head-canon for multiplayer in Halo 5.

-Takes place after the end of Halo 5
-Infinity is staying still in hiding while Spartans train.
-Use of REQs is to give training for as many different weapons and vehicles Spartans might come across as possible.
-Warzone is used to train Spartans for any possible battles against enemies of the UNSC (Prometheans, Covenant Remnants, and Human Allies to Cortana)
-Infection is training for the possibility of any Flood encounters.