Enter the Dragon

Enter the Dragon is a Chapter 3 main quest in The Witcher 2: Assassins of Kings, set in Loc Muinne on both paths. After the summit is thrown into chaos, a dragon appears over the city and Geralt climbs a tower after Síle de Tansarville, whose taunts echo in his head the whole way up while the dragon tears holes in the walls around the stairs.

At the top, Síle is trying to escape through a megascope. She admits the Lodge’s part in King Demavend’s murder, denies any hand in Foltest’s, and names Letho as Nilfgaard’s man, but her teleport goes wrong because someone swapped in a flawed diamond. Geralt decides whether to help her, then ends up riding the dragon out of the city and bringing it down in a crash landing. The final call is whether the dragon lives or dies, and what that means depends heavily on which path you took. Either way, the road leads to Letho.

Walkthrough

Meditate first if you want to apply oils or drink potions, then climb the tower after Síle.
On the stairs, the dragon breaks through the walls; wait for each fire blast to end and hit its head while it is stuck in the breach (four chances on the way up).
At the top, talk to Síle in the megascope and decide whether to remove the flawed diamond.
Fight the dragon on the tower top; Quen with heavy strikes and rolls, or ranged Igni, both work. Damage dealt on the stairs carries over.
After the dragon ride and crash landing, choose to kill or spare the dragon.

Quest Consequences & Choices

Remove the flawed diamond and Síle escapes alive; leave it and the failed teleport tears her apart.
Iorveth’s path with Philippa saved: Geralt can use the dagger to free the dragon, which is Saskia under Philippa’s control; she then talks with Geralt and Iorveth.
Iorveth’s path with Triss saved: Geralt chooses whether to kill the dragon or leave it under Philippa’s control; Triss leans towards killing it.
Roche’s path: Geralt never learns who the dragon really is and simply kills it or leaves it alone.
Sparing the dragon follows the witcher code against killing sentient beings; killing it is recorded as one of Geralt’s greatest feats. Both lead to the reckoning with Letho.