Fight to the north side of the Tower and rendezvous with Amanda Holliday.
Go through the door that opens to the right of where the Cabal landed. Beyond that, you will encounter a Incendior.
Through the door you will encounter more Incendiors. Defeat them, aiming for the tanks for quick kills.
Head through the door in the back of the area and head on through them. On the other side you will find more Legionaries.
On the far side you will find more Legionaries and a Incendior and a major, Honored Centurion. Using a Heavy weapon can make a fast fight here. Using any Solar weapons will quickly defeat the Honored Centurion.