Free the Blue Sage was a mission that Jak and Daxter completed to obtain a power cell in The Precursor Legacy. One of four sages that was kidnapped by Gol and Maia and brought to their citadel until Jak freed him from their captivity in this mission.
The PlayStation 3 and Vita versions of this mission are related to a trophy named "No, Set Me Free!", completing this mission will reward you with a bronze trophy.
The entrance to this area is the second left from the entrance of Gol and Maia's citadel and features a colored platform bridge three squares wide. Once inside, there will be a hovering platform just ahead of you. Using this, you can transport yourself to the other side of the room and onto the second platform before roll-jumping up onto a large, turning, metal platform.
A short trip on the hovering platform to your left sees you reach another turning platform with a large machine firing red blasts onto its surface. To get past this obstacle you must either dash past on the side or grab the ledge and wait for the platform to turn you around; whereupon you may descend onto the wooden floor below.
A large circular platform lies ahead and the next platform is hovering on the right, a considerable distance away; timing is key here. The next jump is also very long; luckily there is enough room on this platform for a roll-jump.
The next section requires blue eco, use the vent close at hand. Collect it and make your way up the five rising platforms, keeping in mind that they will tip depending on where Jak is standing on them. Having reached the final wooden platform and hop onto one of the small square platforms ahead. Jump onto the platform ahead when you pass under the machine's blasts to avoid getting hit; dismount before the platform vanishes back underneath the machine and proceed through the door ahead.
Smash the generator on the left to collect a power cell and free the Blue Sage.