The task of preparing the phylactery fell to Lambert, to his great dissatisfaction. His discontent came as no surprise to me when I learned of it - Lambert was not the most obliging of fellows, and Yennefer, well, let us just say she was not his favorite individual. Nevertheless, Lambert agreed to do the job, and Geralt felt he had no choice but to accompany him.
Geralt and Lambert braved the dangerous path to the Circle of Elements, which took them across a drowner- and foglet-infested lake, through the cave in which Old Speartip slept, and over mountain passes home to mistrustful and treacherous rock trolls. Along the way all the differences between Geralt and his younger comrade were exposed in sharp contrast. Sparks flew between them more than once, and biting commentary and barbed remarks were the order of the day. Geralt tolerated Lambert's prickliness with admirable stoicism, for he knew that the younger witcher's famous sarcasm served only to cover his many deeply-felt, never-healed wounds.
After making it through the cave, Lambert will comment about how Geralt dealt with Nilfgaardians preparing to execute a village witch with Vesimir. This references the events of the "Killing Monsters" trailer of the game.
Checking out where the boy's voice comes from is optional, Geralt can decide on this through dialogue with Lambert.
Killing Old Speartip is also optional. One can sneak through the cave without confronting the cyclops. However, smashing through rocks using Aard could possibly wake Old Speartip, making the confrontation unavoidable. Fortunately, all the obstacles can be climbed over.
If you choose to leave your swords with the trolls, when you later get them back the game will equip two random swords from your inventory. Remember to re-equip your desired swords, or face a potentially nasty surprise at your next fight.
If Geralt uses his Witcher senses at the hut where Lambert originally tied his boat, the secondary quest Monster Slayer can be triggered. It can be completed first before resuming the mission with Lambert.
A Place of Power is revealed during the mission when Geralt and Lambert pass by it; unlike with the other regions, it is not marked on the map with ?.