Lady of the Lake

The seventh and final book in The Witcher series by Andrzej Sapkowski, originally in Polish (original title: Pani Jeziora).

Tropes used in Lady of the Lake include:

Because Destiny Says So: this works to bring all necessary actors to the Very Definitely Final Dungeon, mixed with Stable Time Loop in one case.
Big Badass Battle Sequence: the battle of Brenna. Which in itself has nothing to do with the plot, but is immensely important In-Universe.
- Lower Deck Episode: the battle is shown through the eyes of a minor and unimportant character from Blood of Elves, who now receives the spotlight.
Breather Episode: the hanse's stay at Beauclaire.
Chekhov's Gun: five books of wait, but Ciri's training on the Pendulum now pays off.
Everybody's Dead, Dave: Preceded by a Dwindling Party.
Exact Eavesdropping: and so Geralt knows now what to do, purely by accident... or destiny.
Five-Man Band: Geralt's original troupe from Baptism of Fire is expanded with The Sixth Ranger-slash-The Chick Angouleme, Dandelion leaves the gang, and Regis gets briefly promoted to The Lancer, when he starts feeding on humans again and Cahir suffers a bad case of dead.
Gainax Ending: Geralt and Yen die... and they are on island of Avalon at the same time? Or is it the afterlife? Avalon? And Ciri leaves for Camelot, with Galahad? The author clearly decided to Torch the Franchise and Run.
The Hero Dies: And his love interest, too. However, in the video games, both come Back from the Dead five years later.
Idiot Ball: Vilgefortz, who despite all his power apparently can't notice a well-crafted illusion until it's too late.
Leave Your Quest Test: Beauclaire for the heroes, but especially for Geralt. Dandelion stays.
Let's Get Dangerous: Though he had his moments before, it's now that Regis shows what he can do in spectacular fashion.
Life Will Kill You: Geralt battles monsters, omnipotent sorcerers, leads an army to victory, survives a Suicide Mission... and is killed with a pitchfork by an angry mob. Just a moment later, Yennefer (who also duked it out with aforementioned omnipotent sorcerers and stood up to an entire coven of witches) dies from magical overexertion while trying to heal him.
Lost in Translation: In-Universe example: During their last conversation, Emperor Emhyr bids Ciri farewell in the Elder Speech, addressing her as "luned". Ciri understands this word literally as "young girl". Its second meaning in the Elder Speech, however, is "daughter", which is what her biological father really meant.
The Multiverse
Party Scattering: At the end, Geralt and Yennefer end up Not Quite Dead on opposing ends of the known world and Ciri is Trapped in Another World altogether.
The Promise: Yennefer makes Emhyr promise to never make "her daughter" cry, as she and Geralt are about to commit suicide and Ciri, taken away to marry the Emperor. Guess what Ciri does the moment she is told that she has to part with Geralt and Yennefer again. It actually makes Emhyr abort all his plans for Ciri, turn around, and leave.
Stable Time Loop: while Ciri travels The Multiverse in search of her home, she receives unexpected help from two sorceresses from her future - they realize that being lost between times and spaces, she is, in practice, everywhere. Thus, she may as well appear to them. So by some effort on their side they summon her, and show her the way to her destiny - the Very Definitely Final Dungeon.
Storming the Castle: The final battle.
Two Girls to a Team: Geralt's hanse after Angouleme joins him.
Very Definitely Final Dungeon
The Wild Hunt: It's Aen Elle, elves from another world, who travel between the dimensions to kidnap humans for later enslavement.