What actually happened in the House of the Dragon Season 3 finale? (Spoilers)

Seeing the finale trending. What went down, in broad strokes, without me having to read a dozen recap articles?

Spoilers ahead. The Season 3 finale, "The Queen Who Ever Was" (airing August 9, 2026), centered on the Battle of Tumbleton, where Daemon led Rhaenyra's forces — including Roddy the Ruin and the Winter Wolves — against Ormund Hightower's fortified position, ultimately routing Team Green's forces there. Away from the battle, the episode delivered one of the season's biggest gut-punches: Helaena Targaryen dies by suicide after Mysaria tells her that her young son Maelor will remain a hostage indefinitely — a genuinely controversial creative choice among fans and critics, since it isn't how the character's arc plays out in George R.R. Martin's source material. Maelor himself is also killed, torn apart by a mob amid the chaos. The episode closes on a major turn for Rhaenyra: rattled by news that her exiled brother Aegon is alive and has reclaimed his dragon Sunfyre, she publicly declares herself "The Prince That Was Promised" — a prophesied-hero title with no basis in the books, which showrunner Ryan Condal has said was a deliberate choice to show Rhaenyra sliding toward the tyranny and unpopularity that's referenced, but never fully shown, in the historical text the show is based on.