WARNING: The following contains spoilers for Season 4, Episode 14, "Savagery," and Episode 15, "Sole Salvation," of Attack on Titan, now streaming on Crunchyroll, Funimation, Hulu and Amazon Prime.
For many years, the dreadful Titans have laid siege to the walls of the Paradis Island city, and the defending Eldians have been grimly accustomed to defending the walls with cannons and soldiers armed with ODM gear. But what are they supposed to do now that Zeke has cultivated more of his own Titans inside the walls?
Titans are not a product of nature. They are the Eldian people transformed into monsters thanks to the historic power of Ymir Fritz, and any powerful party can make and use their own Titans at will to destroy their enemies. That's what Zeke Yeager is doing now in the final season, in fact. He schemes to use the Founding Titan for the Rumbling (as far as we know), and this wine is a fine way to see that plan through to the end. And as of Episode 14, we also have some indication of just how many would-be Titans are under his command.
How Zeke Laid The Groundwork For His Plan
The Marley Empire relies on more than a few weapons to wage war with its enemies. This technologically-advanced empire does have soldiers, tanks and zeppelins, but it also has the power of the Titans, forcibly transforming its Eldian civilians into Titans as needed -- especially the Titan Shifters. However, Marley's enemies are catching up, so the Marley Empire has begun to use trickery, such as gas and spiked wine, to maintain its edge. A flashback made it clear that the Marley Empire will send groups of Eldians into foreign nations in human form, then feed them Zeke Yeager's spinal fluid in wine to prime them as Titans. When Zeke performs his shout, the Eldians will transform into Titans right where they stand and unwittingly take the enemy by surprise. An entire nation was toppled this way when Eldians transformed in the capital city.
Now, Zeke is using that strategy for his own purposes, without involving the Marleyan Eldians or Marley leaders. Instead, Zeke brought several cases of fine Marleyan wine with him to Paradis Island and the Eldians there loved it as a tasty novelty -- including many officers and soldiers alike. Right now, Eren and Levi are on a collision course over Zeke, but Zeke just got the edge by transforming Levi's comrades into Titans via that wine. But the real kicker is the alarming number of officers and soldiers in the city who had also consumed the spiked wine also feel the effects. Though they don't fully transform, we see a large amount of them freeze up as the shout happens. (It would seem that Zeke's shout gets weaker as the targeted Eldians get further away.)
How Zeke Can Keep Using This Power
By now, Mikasa, Hange Zoe and the others have figured out the wine trick, but that won't stop Zeke's plan. Once the spinal fluid is consumed, an Eldian is irreversibly primed to become a Titan, and if Zeke escapes Levi's wrath, he can cash in on that. If he survives his encounter with Levi, Zeke could make his way back to the city, unite with Eren, and threaten to perform another shout if his and Eren's demands are not met. Though we don't know exactly how many have been affected, Episode 14 hints Zeke's poison could be shockingly widespread. Zeke could demand that all of Eren's Yeagerist followers be allowed to exit the city with them to fight Marley, and Zeke could even take Dot Pyxis and other leaders prisoner.
These wine-based transformations are a double whammy for the Paradis Island soldiers since this means not only facing new Titans but also losing allies in the process. This process could rapidly turn the tide in Zeke's and Eren's favor, and the wine has already done its job. Levi only survived because he is, well, Levi. But the other soldiers might not get off so easily. Zeke's "I'll shout if you don't obey me!" threat carries serious weight. Will he make his move?