Game of Thrones season 8, episode 4, "The Last of the Starks," concluded with a tense standoff between Queen Cersei and Queen Daenerys, ending in the horrifying execution of Daenerys' loyal advisor Missandei. Given an opportunity to say any last words, Missandei had only one word to say: "Dracarys" - a High Valyrian word meaning "dragonfire." It will be familiar to Game of Thrones fans, as it's the word Daenerys says to Drogon when she wants him to unleash fire on her enemies.
"Dracarys" has additional meaning for Missandei, however, as it's the word that marked the end of her slavery - and the end of her beloved Grey Worm's slavery as well. When Drogon was still a baby dragon, Daenerys offered him to Kraznys mo Nakloz, a slave master in Astapor, in exchange for his entire army of Unsullied. It was a trick, however, as dragons are not pets or slaves, and Daenerys had Drogon burn Kraznys to a crisp by uttering the word, "Dracarys." This was followed by the slaughter of all the slave masters in Astapor, and the liberation of all the slaves in the city.
We can also interpret "Dracarys" (and certainly Daenerys will interpret it this way) as an instruction to the Mother of Dragons to unleash dragonfire on King's Landing. The final scene of this episode marked the last chance to avoid conflict, as Daenerys had earlier in the episode decided that she would hold back and offer a chance for peace - if only to show the people of Westeros that Cersei is the true monster, not her. Missandei's death is a tipping point; Daenerys will no longer accept a mere surrender from Cersei, and Grey Worm will likely stop at nothing for revenge.
Unfortunately, as Varys observed, there are a lot of innocent people standing between Daenerys, Grey Worm, and their revenge - and it's those people who will suffer the most in the conflict to come. Daenerys' forces are still exhausted and licking their wounds from the Great Battle of Winterfell, and King's Landing now has Scorpions (mini ballistas like the one used to kill Rhaegal) mounted on its walls. Simply getting into the city will be difficult enough, and getting to the Red Keep without citizens getting caught in the crossfire may be impossible. Even if Daenerys can defeat Cersei and take the Iron Throne, will the people support a queen who introduced herself to them with fire and bloodshed?
Worse still, "The Last of the Starks" saw Daenerys teetering on the edge of succumbing to the same paranoia and madness that consumed her father, and Missandei's death may well have driven her beyond the point of no return. If Daenerys becomes the Mad Queen in Game of Thrones' final episodes, then both Jon and Tyrion may be forced to make a hard decision about the ruler they've pledged their loyalty to.