Star Wars: The Old Republic offers up eight different classes, and each of these classes can split off into two different Advanced Classes. This design allows for a lot of flexibility and you'll soon realize you're able to specialize in either a damage or a support role no matter what Advanced Class you end up picking, well, almost. Enter the Sith Marauder, a dual-wielding Advanced Class available to the Sith Warrior. The Marauder is all about damage -- regardless of what specialization you pick. You're all about dealing death, and you can pick from three different ways of doing it!
The Marauder uses the Rage resource as its main mechanic. As the Marauder attacks, he builds Rage, and certain abilities can be activated to spend that Rage. Additionally, Marauders build stacks of Fury when using Rage spending abilities or killing enemies in combat. You can gain up to 30 stacks of Fury and can spend all 30 stacks on a variety of short duration self or team-wide buffs.
Playing as Annihilation:
Annihilation is a great set to play in PvE. Early on, when your talent points generally don't make the most impact, Enraged Slash from Annihilation will give you the most bang for your buck no matter what specialization you ultimately end up going down. Obviously, if you plan on actually going down Annihilation it just brings you that much closer to goodies like Deadly Saber and Annihilate. The front-loaded damage is still pretty good early on in Annihilation, but what is great is the extra mitigation provided to you from the bits of self-healing you can do with abilities like Berserk in Juyo form or talents like Hungering. You'll want to open up with the standard Force Charge to Battering Assault to get as much Rage at the beginning of the fight as possible. Keep Rupture up (but let it run its course) on your target and keep Deadly Saber going as often as possible once you pick it up at level 20. Of course, once Annihilate comes into the picture you'll want to keep that going as well. Don't neglect the talent Subjugation, as it will reduce the cooldown of Disruption (your interrupt) to 6 seconds, affording you valuable additional survivability in many solo situations and allowing you to take some of the pressure off the tank in group situations.
Annihilation is a great specialization to go down as a Marauder, but it's really all about juggling cooldowns, both active ability cooldowns and optimizing your passive proc-based cooldowns. Also, be sure to stack Accuracy and Crit/Surge to take advantage of the critical heavy nature of this specialization. Accuracy (up to 110%) should be your first priority. If you can't hit, you can't crit!
Playing as Carnage:
Carnage is a bit more straightforward than Annihilation, but that isn't saying much since Marauders generally have complex skill rotations compared to most classes in the game. With that said, you're mainly concerned with feeding your hunger for Rage as you'll be running near empty a lot of the time with the way you tend to dump Rage. Unlike Annihilation, you'll want to open up with Force Charge into Massacre so that you can benefit from the Ataru strike on Battering Assault. From there, it's a matter of maximizing the use of the Gore buff and Berserk as often as possible. This means Gore to Ravage on cooldown and Gore to Force Scream/Massacre spam when Ravage is down. Like Annihilation, if you time your proc effects and active buff abilities correctly, you'll be putting out some significant damage as a Carnage specialized Marauder.
Playing as Rage:
Rage is truthfully more of a PvP specialization than a PvE specialization, but as far as PvE goes it's probably the most standard of the lot. You'll want to use Force Crush and Choke on cooldown. Spam Vicious Slash along with Berserk whenever you can when facing a single target or Smash when facing a group of enemies. Ideally, you'll want to weave Smashes in between Force Chokes and Force Crushes to take advantage of the significant damage buff provided by the Shockwave talent.
The Marauder Wrap-Up
Marauders are a user-intensive class that really brings the pain when wielded in the right hands. They aren't as straightforward as some of the game's other classes, but if you take the time to master this class you'll find it to be a very rewarding experience. However, the major disadvantage to playing a Marauder is the lack of flexibility afforded to other Advanced Classes. Sure, you can pick from a number of different ways to kill things, but if you feel like you might want to alternate between tanking and doing damage, you should definitely consider the Sith Juggernaut instead.