Was Daenerys Targaryen's attack on King's Landing in Game of Thrones season 8 Lady Olenna Tyrell's parting shot against the Lannisters? Game of Thrones' controversial final season isn't fondly remembered by fans, and the burning of King's Landing played a big part in that divisive response. Jealous of Jon Snow's claim to the throne and unsure of her ability to inspire loyalty, the classic Targaryen paranoia takes hold. Instead of heeding Jon and Tyrion's advice and besieging the Lannisters without hurting the regular folk of King's Landing, Dany puts her last surviving dragon to work and burns the entire city to the ground with ruthless fervor.
Come Game of Thrones' final season, Lady Olenna Tyrell has long since passed. Memorably played by Dame Diana Rigg, Olenna was the matriarch of the noble House Tyrell, and attempted to marry her family into power, first by aligning with Renly Baratheon, then the hateful Joffrey, and finally the not-so hateful Tommen. But in the words of Cersei Lannister, you either win or die in the Game of Thrones, and Olenna's scheming, as deft and cunning as she might've been, spelled doom for her family. Margaery, Mace and Loras are all killed by Cersei's wildfire attack in season 6, and Jaime leads the sack of Highgarden the very next season, effectively wiping out House Tyrell entirely.
Lady Olenna Tyrell's final moments rank among the best farewells in Game of Thrones history. Defeated, but still dignified, Olenna shares a brutally honest last conversation with Jaime, and delivers a withering assessment of Joffrey in one final middle finger towards House Lannister. But what if Olenna's parting act of revenge wasn't just calling Joffrey a "c**t," but setting events into motion that would result in the total destruction of King's Landing? When Olenna meets Daenerys Targaryen at Dragonstone in Game of Thrones season 7, she expresses her admiration for the Mother of Dragons. More importantly, she tells Daenerys "peace never lasts...are you a sheep? No, you're a dragon. Be a dragon." At the same time, Olenna advises the Queen not to put stock in the words of Tyrion.
At face value, the scene is nothing more than Olenna telling Dany to trust her instincts and remain a woman in her own right, instead of being led by men. Potentially, the quote is much more; perhaps Olenna is intentionally provoking Daenerys into showing no mercy when she finally makes her move on King's Landing. Aside from Littlefinger, Lady Olenna is the best long-term strategist in Game of Thrones, even masterminding the death of Joffrey Baratheon. She uses the weaknesses and desires of others to her advantage, and her appearance causes enemies to drop their guard. It certainly wouldn't be beyond Lady Olenna's capabilities to sow the seeds of revenge a whole season ahead of time, ensuring Daenerys would carry out revenge for House Tyrell even after Highgarden itself had fallen.
Watching the Dragonstone scene with the hindsight of Game of Thrones season 8, Olenna's words certainly carry more weight. Lady Tyrell waits until she and Dany are alone before imparting her sage advice, and then plays exactly the right notes to bend the Queen to her will. Olenna appeals to Daenerys' female pride by telling her to ignore Tyrion, then prods at her insecurity by arguing that a peaceful resolution is impossible. Finally, the matriarch invokes the spirit of the dragon to fire up Daenerys' aggression. Every word is designed to lead Dany towards a full-scale attack, and the Mother of Dragons herself even notes that revenge against Cersei is Olenna's chief priority, rather than revolutionizing Westeros.
Even without Lady Olenna's encouragement, Daenerys Targaryen likely would've still turned bad in Game of Thrones season 8 due to her failed romance with Jon Snow and the insecurity she was already feeling after making the journey from Essos. But knowing that Lady Olenna Tyrell helped Dany along her path adds an extra wrinkle to the Queen of Thorns' death scene in season 7 - and perhaps explains why she accepted her inevitable demise so calmly. The death of the Lannisters had already been ensured.