This post contains spoilers from Game Of Thrones Season 7, Episode 3. Game of Thrones Season 6 was notable for the sheer scale of death in every episode. With the exception of "Blood of my Blood," every episode contained multiple deaths of named characters, from Doran and Trystane Martell in the premiere all the way to nearly the entire Tyrell household in the finale. Season 7 has gotten off to a slower start, but a huge death came in Episode 3: Cersei kisses Tyene with poison on Game of Thrones and her death is imminent.
In terms of an entrance, Euron's marching his prizes through the streets of King's Landing made quite the impression. (I mean, who doesn't love a parade?) But the question was, how would these prizes go over with Cersei Lannister? She all but sent Euron away with the promise she'd consider marriage for the right price. Are two Sand Snakes and Yara Greyjoy the right price? Does Cersei even want Yara? And what in heaven's name will Jaime make of all this?
In the end, Cersei was quite pleased with at least two of these prizes. To be fair, she didn't really need Obara or Nymeria -- they were extraneous anyway. It's Tyene who is known for poisons, like the one that killed Myrcella. And its Ellaria who was the one who delivered that deadly kiss back at the end of Season 5.
Also, and this is something the show has sort of failed to emphasize in the last couple of seasons. Tyene is, at least in the books, Ellaria's daughter by Oberyn. Obara and Nymeria are supposed to be the children of other lovers before her. The show seems to treat all three like full sisters, which kind of loses the impact, but the point is here that Tyene is supposed to be Ellaria's only daughter. Just like Myrcella was Cersei's only daughter.
You can see pretty quickly where this is going. Ellaria murdered Cersei's only daughter, and made it so Jaime had to watch her die helplessly. Cersei is merely returning the favor. Sealed with a kiss.
Tyene, like her sisters last week, "ironically" dies by the only feature we know of her -- her weapon of choice, poison, thanks to Qyburn. And that was the end of the Sand Snakes.