While the City was preparing for an assault by the combined forces of all the Fallen houses,
tensions between the Speaker and Vanguard Commander Osiris reached a breaking point. Zavala,
having recently become the Titan Vanguard by replacing Saint-14, attended a meeting of the Consensus
without Osiris present. When the New Monarchy representative protested that Osiris was absent, Zavala
announced that Ikora would be filling in for Osiris. The Speaker asked her to formally become the new
Warlock Vanguard, which she accepted. The Speaker then proclaimed that he was exiling Osiris from the
Last City and thus named Zavala as the new Vanguard Commander in place of the troublesome Warlock.
When Zavala learned that the Hunter Anastasia Bray was investigating her past life, which Guardians were discouraged from doing, he confronted her in the Tower's plaza. He told her that in addition to the inappropriateness of keeping her previous life's name, he believed her research was causing her to neglect her duties to the Last City. Ana argued that her past was useful to the Last City and may be why the Traveler brought her back, but Zavala countered that she was brought back to be a Guardian and fight for the future. Their argument was interrupted by the Hunter Vanguard Andal Brask, who informed them that the Fallen were assaulting Twilight Gap.
Zavala led the Battle of the Twilight Gap against the Fallen, fighting alongside Ana. She continued to try to convince Zavala that her research was worthwhile, but was attacked by a Fallen Captain. Zavala ordered her to fall back and attempted to cut down the Captain with his Thunderlord, but Ana was knocked off a cliff by the Captain and believed dead by Zavala and the rest of the Last City in the aftermath of the battle.