There're no actual quests in the Epilogue (besides the main "The Assassins of Kings" quest) and the main decision that you have to make is either kill Letho of Gulet, the kingslayer, or not.
The Plot behind the Assassinations[ | ]
In the end when you finally meet Letho he explains to you that he fulfilled the plan developed by Emhyr var Emreis to "soften" the North before the upcoming invasion.
Letho's Fate[ | ]
You can either kill Letho or let him live. You don't gain anything by killing him, though thus you can have "the final battle" which is compulsory for many games.
It you spare him than as the journal says his fate is "story for another time".
Endings[ | ]
Geralt and Triss (Roche's Path)[ | ]
If Geralt chose to save Triss, after defeating the dragon she meets him on the wall and tells that Letho is waiting at the main square. Later they meet Roche who is declared a criminal in Northern kingdoms. He is not pleased that Geralt didn't help him save Anais and that Dethmold could escape.
Vernon serves Redania (Roche's Path)[ | ]
If Geralt chosed to save Anais then after defeating the dragon Vernon Roche meets him on the wall and tells him that Letho is waiting at the main square. If after "For Temeria!" quest you advised Roche to give Anais to Radovid, than he wears a Redanian uniform and tells you that he now serves king Radovid. When you meet Letho on the main square you finally meet Triss. She tells you that Letho saved her from Nilfgaardians and then from soldiers that started killing mages and raping witches after the chaos caused by dragon erupted.
Enhanced Edition Endings[ | ]
Witch Hunt in Loc Muinne[ | ]
This event occurs if you choose to help Roche rescue Anais or help Iorveth free Saskia. The Lodge of Sorceressess is condemned by Radovid, and a bloody witch hunt ensues in Loc Muinne.