Anyway,
I think Agni will/might save Gandharva and the rest of the city, or he might just kill him, but I really hope not since Gandharva right now in sura form has the equivalent power of a god and more so, Agni on the other hand is tied by the contract with Bilith which further limits his power. Of course he might take the sword of Re and have a go at it, since he's immortal in a way which the sword would not affect him. Still, Agni values friendship, at least I hope he really does and sees Gandy as a friend. If Agni does save Gandy somehow without a death battle I think Gandy would join up with Agni and his team as he really doesn't have any further loyalty towards god Kubera with finally accepting his daughter's death. This would benefit Agni. Actually, I think no ones on god Kubera's team anymore, not even god Kubera himself. So it'll just be Sagara and co.
As for Teo, although I really wish she was alive, I guess there maybe are limits... But who knows? Agni might feel something similar with the situation and decide to go kill death god again, there's nothing wrong with breaking the rules when you've already broke them before. Still, it's more likely it won't happen.
The worst that could happen is that Gandharva and Agni both died in a life-death battle, both priestesses died as well, Bilith from Agni's power over usage and after everybody died Sagara stood over their corpses and laughed like a maniac. (crosses fingers)