However, Commander Jane Shepard discovered that the Citadel was the Catalyst, it was the missing final component which was necessary for the activation of the Crucible. The Crucible is an ancient and highly complex device constructed as a superweapon to stop the Reapers, so they must take back the Citadel by get to the Conduit (Citadel beam) on Earth. The Conduit is a miniature mass relay, it is essentially a 'back door' onto the Citadel, which is the hub of the Relay
However, Commander Jane Shepard discovered that the Citadel was the Catalyst, it was the missing final component which was necessary for the activation of the Crucible. The Crucible is an ancient and highly complex device constructed as a superweapon to stop the Reapers, so they must take back the Citadel by get to the Conduit (Citadel beam) on Earth. The Conduit is a miniature mass relay, it is essentially a 'back door' onto the Citadel, which is the hub of the Relay