Borderlands 3: Siren Song

[Part of the Wasted Land story]

After some quick study, Tannis is fully sirened up and destroys the defenses to the Calypso's Cathedral and main base, letting the united Crimson Raiders attack the compound where Ava slays Troy, avenging Maya and absorbing his energy which activates her latent siren gene. Tannis takes her as her apprentice.

Unfortunately Troy had already begun unlocking "the Great Vault" having discovered that the moon was actually the key. Within was meant to be a universe destroying creature that his sister Tyreen wanted to absorb to cement her godhood - she was just running an errand on an Eridian homeworld to kill her father while waiting.

With that out of the way Tyreen warps back to Pandora only to find Lilith and Moze already waiting for her and is wiped out easily by the Mechwarrior. Alas the moon is now too close to Pandora and there's no stopping it anymore except through self sacrifice. Taking her siren powers back from Tyreen's corpse, Lilith becomes the Firehawk once more and uses her gift to fly up and then self detonate on the moon, pushing it away - resealing the Great Vault and saving Pandora.

Will we ever see her again? Probably because there's that Borderlands movie coming out.