Asajj Ventress: Blue Shadow Virus
Do the usual hack-and-slash routine until you reach two robots guarding a switch panel. Une a clone lay a bomb there and jump in the hole that appears.
From here, run down the corridor and use the Force and grapple hooks to close down all the jail cells that appear to the left and right. After the two unkillable robots appear at the end of the tunnel, switch to your other characters per the on-screen instruction.
As Obi-Wan, jump into the cannon and shoot down the shielding devices, followed by the central hole cover. Your ship will then glide down toward the hole, allowing you to jump in.
Head to the right and use the Force to disassemble the purple contraption above. That will create a hole in the floor; jump down into it to destroy the "unkillable" robots from earlier and join the rest of your party.
Use the resulting rubble to create a switch, and activate it with Captain Rex. Remain as Rex in the next room and pop the grappling hook on the back-left wall. Stand on the platform that appears as Ashoka and use Obi-Wan to Force you up. Cut a hole in the wall in front of the increasingly recognizable jedi icon. Destroy the electrical components inside. Cue the introductory Jar Jar Binks cutscene.
As you run down the hall, once again use the Force and grappling hooks to close to jail cells to the left and right. When you reach a fork in the road with two shielded robots, turn right to activate a jedi symbol and cut your way through to a mini-boss.
Use the Force to throw any objects you can at the guy on the high platforms. After five hits, you'll trigger a cutscene, but the battle isn't over yet.
Now that you've freed Jar Jar, you can jump higher and reach the top platforms. Grab the switch above to open a passageway, leading to more mayhem.
Walk forward to trigger the cutscene, then use a jedi to ascend up the wall to the left. Stand on one of the red buttons, and Jar Jar will automatically come to get the second one.
The enemy here will hide in the various bushes, but you can easily track him and, even if you lose him, he'll shake the bush to let you know where he is. Attack the bush to expose him and then attack him. Repeat until he's out of hearts.
Follow him to the next room. Here, don't worry about the droids because you'll easily be able to take out the little guy. Just keep attack him as he runs back and forth between the same two spots.
When you defeat him, rearrange the pieces left behind and pull the switch. Now it's time to go back to your other characters.
Head right through the tunnel and do the whole cut-out thing when you reach the door. Now it's time to finish off the boss from earlier. Catch his bombs and use the Force to deflect them back to him. Five hits later, your battle is complete.