[quote]SO. My question is: If the Flood suddenly invaded the Last City, and we got to fight against Flood Fallen, Humans, and Cabal, what would happen? Would we win?[/quote] If we caught them early, as in before any major infections or before a Gravemind can be created, then it's possible. However, the City itself would be at a high risk of being lost if the Flood managed to breach it. [quote]Another terrifying thought is [i]would the Hive and Flood become one?[/i] I’m in a doozy imagining the possibilities.[/quote]Flood Hive, or Hive Flood, would certainly be scary to think about, but it certainly wouldn't be mutual symbiosis. Parasites generally don't get along with each other. [quote]Edit: Would a Guardian keep their light after being infected? Are Exos and Taken Immune? Maybe the Flood and the Hive would attack each other like rival insect nests?[/quote]If the ghost is unaffected, then an infected Guardian could probably be destroyed then reconstructed without much issue. It's unfortunate that we could never see a similar case since Asher's ghost was corrupted by the Vex. On the topic of other races though, I'd see it like this: Fallen/Eliksni would ultimately be Flood Food. They don't have any lightbearers or paracausal warriors to hold the line like Humanity and the Hive/Taken, nor do they have the same brute strength as the Cabal (from a numbers and tech standpoint). With their current numbers and generally unstable organization, they'd be consumed quickly. The Cabal could quickly end them early by outright nuking them or keeping their distance. However, if the Flood could establish any Graveminds then the Cabal's chances of winning become much smaller. If the Cabal were to lose though, they'd probably last longer than they did against the Hive. The Hive have an edge with their paracausal powers, and could probably be one of the only races to outright beat the Flood if they fight accordingly. However, this would come down to how the Hive plans to deal with them; if we talk about the pre-TTK Hive specifically, then they could certainly beat the Flood thanks to Oryx/Xivu Arath. The Taken might not be infectible, or at least not easily, and it wouldn't be surprising if they tried Taking the Flood to some extent. If the Taken can somehow manage to Take a Gravemind in particular, then the Flood would most likely lose in the long run. The Vex are perhaps the most interesting as they are effectively what the Flood could become: the ultimate (or at least final) life forms in a universe without space magic. The rest is in spoilers because I decided to go into length on it: [spoiler]The Vex are the result of a repetitive pattern that always wins in the Flower Game, so one could assume that they should have the capability to defeat even a predatory parasitic species like the Flood. The Vex are also significantly more technologically advanced than the Flood to the point where they have pseudo-time travel, incredibly advanced and massive processing power, planet-sized reality prediction engines, teleportation on some near-unfathomable level, etc. Infecting the Vex would likely be difficult for the Flood since the Vex themselves are a microorganism fluid that is dangerous just to the touch as they can also infect individuals through self-replicating subroutines. Basically, the Vex can "no u" the Flood too. Even if the Flood can infect the Vex though, their subnets are programmed to run separately from the rest of the network to optimize functionality and perhaps reduce being compromised on a large scale, thus the entire network will generally not be threatened except by very powerful paracausal beings like Oryx. Now this isn't to say the Flood can't ever beat the Vex, but looking at each of their feats, I would say the Vex are more likely to win in the long run.[/spoiler]

Saint would solo them.

If the Flood got on Earth at all, we are well and truly screwed. It's not just the infection forms, combat forms, and carriers you have to worry about, it's the air too. Flood spores can be inhaled, and the infection can begin that way too. Even if Guardians were immune, they'd eventually be guarding a tomb.

Per flood lore, exos would probably fall to their logic plague and possibly ghosts. I've given it thought in the past and i think the vex and taken would have the best chance followed by the hive and scorn. Vex are probably the perfect form since they have machine bodies with an organic core that courses with arc energy which can infect other creatures. No matter how the flood tries to infect them they wouldn't be able to since infection forms would be electrocuted and spors would dissolve. Their biological cores would protect them from logic plagues. Plus they infect plants in a matter that kills all life. Meaning no biomass for the flood to build with.

We cant even manage a few thrall and screebs so no we are all dead. Unless you lag switch and then all is good.

The Flood wins. It isn't even remotely close. They're the Taken on steroids, and the Hive pushed Guardians off of the moon.

consume~enhance~replicate

One of the most terrifying things about the Flood is that it can even infect non-biologicals, AI, with something called the Logic Plague (basically just Speech 100). Not even our ghosts are safe.

I would say a slow death of attrition would be inevitable. Guardians can be reconstructed by our ghosts and we would be holding the wall so IF the flood was inside the city? We would only have to deal with the human populace and keep them safe. As for taking on other enemy types? Cabal- Would hold out for a long time. They have arsenals of weapons that are good at dispatching enemy types, but they would eventually lose and be consumed. Hive- Honestly... I would ultimately say the hive would like the flood, but would not be allies once they start losing units to them, but would like the regenerative capabilities. Ultimately, the flood would consume them. Fallen- No chance. Vex- The best bet for killing the flood due to no conversion being possible and blast cannons that would rip them apart. Guardians- Stalemate once the flood was in bad positions to come after us and we would be seeking the Gravemind once we found out about it. Taken- Would... convert... the flood. Going with the fun possibility of both being destroyed and possibly controlling them.