Lady of the Lake is the conclusion to the 5-part The Witcher series.

Ciri has teleported, and discovers she has some magical power, allowing her to travel between space and time. She tries to return to her own world, and succeeds.
Meanwhile, Geralt and his companions are still scouring the continent for Ciri, and get caught up in an affair of Dandelion in Toussaint, after being pursued by mercenaries hired by Vilgefortz.

Something I find quite impressive, and admirable, is Sapkowski's accurate style of descriptions. I can imagine myself, standing on the remains of a battlefield, with the crows pecking the corpses, and the survivors moaning for help.
The battle of Brenna is brilliantly described. No romanticizing, no glorification of death or violence, just pure, raw, and frankly unnecessary bloodshed. The battle is told from the the perspectives of poor scribe Jarre, who has found himself in a pike regiment, facing the Nilfgaardian cavalry, to the overworked, and overwhelmed field medics, who're burdened by the countless wounded, and other various generals and ordinary footsoldiers.
Quotes like these, really hit me hard, and realized the horrors of an actual battle:

‘Noooo!’ the wounded man said, thrashing his head, trying to escape Marti Södergren hands. ‘I don’t want you to!’

‘I have to amputate or you will die.’

‘I’d rather die...’ The wounded man’s movements were getting slower under the influence of the healing magic. ‘I’d rather die than be maimed... Let me die... I beg you... Let me die!’

‘I cannot,’ Rusty raised the scalpel and looked at the bright blade of immaculate steel. ‘I cannot let you die. I am a doctor.’

The PTSD and traumas medics are developing, told from the perspective of Iola:

Iola, breathing heavily, swallowed saliva with effort. I’m going to faint, she thought. I can’t stand it. I can’t bear it any longer, the smell, the awful mixture of blood, puke, feces, urine, intestinal contents, sweat, fear and death. I cannot endure it any longer, the constant crying, the howling, the bloody, slimy hands reaching towards me, as if I was their salvation, their refuge, their lives... I cannot stand the nonsense, what we are doing here. Because it is nonsense. On big, huge, meaningless nonsense. I cannot stand any more strain and fatigue. They continue to deliver more and more... I cannot stand it. I cannot stand it. I’m going to throw up. To faint. I will be ridiculed...

The ending. What did I think of it? To be honest, I'm not sure. So to start off, I think the ending has multiple 'parts'. There is the ending of Stefen Skellen, Bonhart, and Ciri's other pursuers. The storyline of Vilgefortz also reaches a climax, where at the end, he (to my satisfaction) gets killed, after killing Regis, and the ending of the companions.

So to start, I really enjoyed the tension at the final battle of Ciri vs Bonhart. I'm glad Ciri was the one to strike the killing blow, as she has been abused, humiliated, and beaten by Bonhart in the Tower of the Swallow.

The company of Geralt, aka Geralt himself, Cahir (who is NOT a Nilfgaardian ;D ), Regis, Milva, and Angouleme, finally split up. Not by the means I liked.

Tragically, Cahir sacrifices himself for Ciri, after having traumatized Ciri as 'The Black Knight', and in my opinion, he redeems himself. He has a great character arc, as a young, Nilfgaardian boy, who hates the Nordlings, because they killed his brother, and he ultimately sacrifices himself for a Northern princess. Great story, and a great redemption.

Regis meets his end at the hand of Vilgefortz, who is apparently always prepared for a vampire attack. I think he's a great example of why not all monsters are actually monsters. Geralt didn't kill him either, when he first met Regis, and not even when he revealed Regis' true species. Regis may be the only 'civilized' vampire, who doesn't drink blood, and doesn't kill humans. He realized there are ways to live without drinking blood, but I'm not going much deeper into this, because this happens during Baptism of Fire IIRC. Anyway, he sacrifices himself for a Witcher; for a person whose job is to hunt down his kind, and to kill his kind; a person who gets paid to do so. Regis' relation with Geralt is fascinating, because despite their natural differences, they get along, and Geralt actually grows fond of Regis, despite him being a vampire. Regis has 'opened' Geralt's eyes, and showed him not all monsters are monsters. He's a great character, with a fascinating backstory, and a noble ending.

Milva's story is concluded ironically, and fittingly with arrows piercing her body. I've personally grown quite fond of the archer, and was disappointed to see the decrease of wholesome moments between her and the other companions. She was a human archer, who led dryad hunters into slaughter, by leading them to places where dryads are already waiting for them. After that, she guided wounded and surviving Scoia'tael to safety, in Brokilon forest. she befriended the elves, and was sympathetic for their cause. When Geralt is brought to Brokilon forest by Triss Merigold, she has to take care of him. She initially dislikes him, but grows fond of him after all. She even offers to go with him; to guide him to Nilfgaard, where Emperor Emhar var Emreis allegedly imprisons Ciri. She, Geralt, and Dandelion set off. She is a really entertaining character. She had some funny and relatable quotes, shuts down all the sexism in an amusing way, and has a great relation with the other characters, especially Angoulême. Her death was tragic, and fitting, nevertheless it shocked, and saddened me. After her death, I became way more suspicious and vigilant for other deaths.

Angoulême, is the final character of the company. After being saved by Geralt from execution, she joins his company, with Cahir, Regis, and Milva. She meets her unfortunate end at the hands of bounty hunter Bonhart, sacrificing herself for Ciri. I really enjoyed her dialogue, and I found her 'aunty' nicknames quite funny actually. I was sad, but not too much, as I had already witnessed the heroic deaths of Milva, and Regis, prior to her death.

As user TARS explains perfectly on Stack Exchange, there are various interpretations possible. Ultimately, I think Geralt died by the pitchfork. Yennefer followed him soon after, and they were reunited into whatever 'afterlife' exists in the Witcher. I think Ciri travelled to whatever universe the death end up in, she teleported them, and all the others who were attending their wedding to a nicer universe, and they lived happily ever after. I was personally expecting this, as the Witcher really follows the start of Geralt, and his end. One could perhaps argue the Witcher series is actually a coming of age novel, since the reader witnesses the growing up of Yennefer, Geralt, and especially Ciri.

I won't bore myself with politics, as I have read enough of it in the books. Frankly, I couldn't care less whether Nilfgaard won or not. In my opinion, this book doesn't revolve around politics (like in A Song of Ice and Fire), but more around several characters trying to find their place in a war-torn world by politics.

Besides that, there's also the occasional wisdom from Sapkowski, and his sigma male grindset:

"They say that Beauclair is home to perpetual banquets, balls, feasts, revelry, and flirtation. They say those activities are just lazy, stupid, and a waste of time that could be spent thinking about business. They say you have to focus on what is really important. On the goal that beckons you, constantly. Incessantly. Without wasting any thoughts on frippery. Then and only then can you reach your goal."

To conclude, I think this series may have just become one of my favourite series, next to A Song of Ice and Fire, Percy Jackson, and Harry Potter. Sapkowski has done an incredible job at constructing this series, and this world, it's like I'm in the world myself!

This series deserves a 6/5, unfortunately Goodreads doesn't allow that.