There are a total of 3 Holocrons. All of them are Costume Holocrons (Red).
1. Right when you start the level, turn around and go behind the stump.
2. When you are in the base and you have to lower the first walkway by throwing your light saber ( + ) and then Force Grip () it down, continue on until you make a left. If you walk forward a bit and look below you, you will see a Holocron on a walkway with the orange currents that injure you. Jump down on the walkway to grab it.
Note: You don't have to kill yourself to continue. You can use force push or force repulse to open an entrance on one side of the spherical power generator, force grip a power pillar up, then go inside and force push an exit before the pillar lowers back down.
3. The last holocron is right before the yellow-orange fences. When you come up to the part where you have to cross a long walkway with the orange currents on the floor and the yellow-orange fences that you destroy with force grip (), turn around and you will see a walkway above you. Jump on the small ledge in front of you and then jump up on the walk way. The holocron is at the end of the walkway.