At the top of its E3 presentation, Square Enix trailer footage for Final Fantasy XIV's Stormblood expansion that dropped last year...and then had bumper footage for another event: A crossover between the MMO and the publisher's best-selling Monster Hunter: World, which came out back in January.
It's unclear how much of either game will be crossing over into the other. All we saw was a colossal dragon and a team of Final Fantasy-garbed adventurers ostensibly facing off with the creature. Odds are that Monster Hunter: World enemies will be added to the online game rather than the other way around, given that other franchises like Yo-Kai Watch have invaded the MMO before, as Polygon pointed out. But with details so scarce, we'll have to wait for news down the line to clarify exactly how much of one game will end up in the other -- but we did see Palicos in the teaser, which is all we really need to look forward to (right?).