Retribution

There are two rounds to this fight.

The first round is extremely easy, using Quinn for heals. Baras doesn't put much effort into the fight.

The second round can be annoying. I got his health down to where one more hit would have finished him, but I missed him casting Emperor's Voice and I was wiped out. Very, very annoying!

Make sure you interrupt Emperor's Voice, while running away from Crushing Field (AoE). Make sure you time these two things well - while running away from the AoE you risk not being close enough to him (or in the correct direction, facing him) to be in range for interrupting his Emperor's Voice ability.

Quinn's carbon freeze ability is a lifeline. Try to keep Baras immobilized as much as possible (use Force Choke and Force Push to knock him off his feet / interrupt), and keep him away from Quinn, otherwise he'll be caught in the AoE. I made sure Quinn was at one side of the room (near the door) while Baras and I were at the other end of the room. I used an Advanced Might Stim before I started the fight, and kept Saber Ward up!

Ince the fight was over, I summoned Jaesa to gain conversation points for her. I gained 20 for Quinn and 307 for Jaesa, and 3353 Legacy points. Chose the Heavy Ciridium Greaves as my reward.

Next mission: http://www.torhead.com/mission/etmydlL/first-strike

Korriban
- Arm Yourself - Level 3
- Judge and Executioner - Level 4
- Slaying the Beast - Level 6
- A New Master - Level 7
- Sith Arithmetic - Level 8
- The Final Trial - Level 11 [Vette]
- Leaving Korriban - Level 11

Dromund Kaas
- The Flight to Dromund Kaas - Level 9
- The Transporter - Level 10
- Pull the Plug - Level 12
- Laying Waste - Level 14
- An Ancient Answer - Level 16
- Leaving Dromund Kaas - Level 16 - [Spaceship & Start Chapter 1]

Balmorra
- Contact Made - Level 15
- Erase the Past - Level 17
- Silence the Son - Level 18
- To Kill a Legend - Level 19 [Malavai Quinn]

Nar Shaddaa
- Seek Your Contact - Level 21
- Disrupt Negotiations - Level 21
- An Army of One - Level 22
- Distress Call - Level 22
- To Kill a Sith Lord - Level 23
- A Threat Leveled - Level 24

Tatoonie
- Seek Answers - Level 25
- Demon's Blood - Level 26
- Oasis - Level 27
- Guru in the Dunes - Level 28

Alderaan
- Shake Down - Level 28
- Knock Knock - Level 29
- Front Lines - Level 29
- Choke Point - Level 30
- Battle Organa - Level 30
- Deal with Kendoh - Level 31
- The Plan is Working! - Level 32
- The Padawan Exposed - Level 32 [Jaesa Willsaam]
- A Sith Lord's Rise - Level 32 [End Chapter 1]
- Set the Table - Level 32

Taris
- Check in - Level 32
- General Frellka - Level 32
- General Minst - Level 33
- General Durand - Level 34
- General Faraire - Level 35 [Lieutenant Pierce]

Quesh
- Ambush! - Level 36

Hoth
- Debriefing - Level 37
- Rescue Lanklyn - Level 37
- Interrogate the Talz - Level 38
- The Master's Weapon - Level 39
- Jedi Master on Ice - Level 40 [Broonmark]
- Power Play - Level 41
- Fanning the Flames - Level 41 [End Chapter 2]
- Declaration of War - Level 41

Belsavis
- Strong Arm - Level 42
- Locate the Enemy - Level 42
- A Mass of Assassins - Level 43
- Thwart the Rescue - Level 43
- Reallocation - Level 44

Voss
- Request and Audience - Level 44
- The Pain of Healing - Level 45
- Pendant of Bone - Level 46
- The Voice of Darkness - Level 47
- The Transponder Station - Level 48

Correlia
- Protect Vowrawn - Level 47
- Squeeze the Spy - Level 48
- Jedi Spy - Level 49
- Baras's Lair - Level 50
- Retribution - Level 50

I did this as a lvl 46 Immortal Juggernaut with Quinn.
What roblucas said helped me a lot.

It was a chance-dance, since my level made me miss a lot and take more dmg than usual, but it's not impossible. Used a stamina stim and rotated my defensive cooldowns, including defense-relics (well, one only actually, cause I lost the ability to use the second, cause I fell in dark side rank *cough* ).
I kept Quinn's carbon freeze on auto.
Try to immobitize Baras a lot, but use it wisely, cause if you miss an interrupt on Emperors Voice, you might want to use another means of disrupting.

Remember all your possibilities to stunn him! Force Choke, Force Push, Backhand, Intimidating Roar!
Depends on your specialization, of course. But think of everything you have.
Keep him away from your companion at all cost! They will be crushed in the AoE. A good way to play this I felt, was to jump in and go to Baras' right, so when he pushed be I'd have a chair in my back. Or if you manage it, you can fight him in the gap on the opposite side of the entrance.

Should you have everything on CD and miss interrupt, you can walk away from the Voice of the Emperor, but it's more risky than interrupting imo.
Good luck!