We know what "gift" Euron plans to give Cersei
At the end of last week's premiere, Euron promised he'd return to Cersei with a badass gift that she can't get anywhere else, and you can be damn sure it's not one of those Kay jewelers "Ever Us" love rings for your best friend AND lover (they're the same person OMG!). Instead, he'll be bringing news that the Martells -- responsible for the death of Cersei's daughter and in open rebellion with her -- are dead. The three Martell girls a.k.a. the Sand Snakes had a lot of fight in them, but giant ax beats whip pretty much every time. Two of the Sand Snakes wind up impaled on and hanging from their ship, while Ellaria and Tyene Sand appear to be part of Euron's sweet gift to Cersei.
Euron also offers Yara, though Euron's plans for her aren't clear yet. He could've killed her right away, so the implication is that she'll become a prisoner. Bad things happen to Greyjoy prisoners, as we've seen. But keeping them alive could also be his downfall -- let's not forget Olenna Tyrell's parting words to Daenerys on this episode: "be a dragon." Ms. Stormborn's plan B could leave King's Landing in ruins and Yara with one more chance of revenge.