The Sentinel Advanced Class is a Pure DPS Melee class with varying degrees of Operations utility depending on the spec. The Watchmen tree brings extra interrupts and a raid wide 6% heal about every 30 seconds if managed well and the Combat tree provides more spontaneous burst and increased Ops wide movement speed from the Transcendence Predation buff.
Unique Sentinel Mechanic: What separates Sentinels from Shadows and Guardians (aside from the fact that Sentinels can't tank) is Centering which is built up by using abilities that spend Focus. At 30 stacks of Centering the abilities Zen, Transcendence and Inspiration become available and are your main raid utility abilities. Zen should be used nearly all the time because of how it affects each spec. Inspiration should be used at your raid leader's discretion, however it it most often used at the beginning of the fight (or shortly thereafter) for the possibility of being used later in the fight. Transcendence is mostly a Defensive/ Mobility skill that shines in PvP but has several uses during boss fights were mobility is key.
Watchmen:
Spoiler
The Watchmen spec is all about juggling cool down timers and making sure you have enough focus to use Overload Saber and maintain three stacks of Merciless from Merciless Slash whenever they are available. Juyo Form is the foundation of this spec. If you have reservations about how dangerously close Juyo Form can bring you to the dark side I suggest that you pick another spec, and if you try to play this spec without Juyo Form at all, well, then there's nothing I can do for you.
A general Watchmen build is 31/07/00 + 3. which gives you every major PvE damage, survivability and utility talent and leaves three points to spend where you feel is best for your group composition. The pure DPS approach to Watchmen Spec though would look something like this, a 31/3/7 build that sacrifices Defensive Roll (almost entirely unnecessary in TFB) to get an extra 15% crit chance with Slash, which if I recall correctly can amoun to around 12-15% of your total DPS.
For the Talents in the Watchmen Tree that I did not take Recompense and Inflammation are most useful in PvP environments since one, you should never be the target of the boss and thus Riposte should never be available for use, and two, the only NPCs that are affected by movement speed debuffs aren't bosses and usually only around in between boss fights. Better known as Trash. I also see Force Fade as more of a PvP talent with limited use in PvE environments because Force Camouflage acts mostly as an Aggro drop with the Stealth and Damage Reduction buff break when Direct Damage (anything not a DOT) is dealt to any target. That said, the movement speed buff and the damage reduction buffs are useful in certain fights (like Kephess), this alone makes it an Optional talent as opposed to a "Never take this talent for PvE ever" talent like the other two.
Insight:: Insight is great because your highest damaging abilities, your burns from Overload Saber and Cauterize, are classified as Force Abilities, and while you get a lot of Talented and Automatic (Zen) Critical chance, the more often you crit, the more damage you do and the more "self heals" you receive.
Steadfast:: Steadfast is excellent because it's free 3% accuracy that you don't have to itemize for, but getting to 100% Accuracy for Melee attacks is fairly easy (only like 150 rating is required). That's why this falls under optional.
Jedi Crusader:: For fights with a lot of AoE damage this is great because Rebuke procs off of any damage received, has a maximum duration of 30 seconds, is on a 60 second cool down and with the talent gives you an extra focus every three seconds that you take damage.
Swelling Winds: This for fights where extra AoE is desired, namely the Trandoshan phase of Kephess.
DPS priority list because rotations are lame. 1.Dispatch: When target is under 30% health. It's your kill shot. Go kill things with it. 2.Overload Saber: This is your highest damage burn, use it religiously. 3.Merciless Slash: Highest damage direct attack that had a 7.5 second cooldown at 3 stacks of Merciless, part of maximizing damage in this tree is making sure you always have 3 stacks of Merciless. Merciless Slash also has a 66% chance to reset the cooldown on Cauterize. 4.Cauterize: Use this off cooldown when available but only when Overload Saber and Merciless Slash are on cool down. 5.Slash: Used as a Centering builder and has a 33% chance to reset the cooldown on Cauterize 6.Zealous Strike: Use off cool down whenever your have less than six focus. 7.Force Leap: Focus Builder plus mobility plus interrupt. Use it as religiously or as sparingly as the current fight requires. 8.Strike: Builds focus. Nuff said.
As an aside: Master Strike may be used sparingly on occasions when you are completely out of focus and Zealous Strike and Force Leap have more than 2 seconds left on their cooldown. It is decent "free" damage over three seconds. I do not recommend that newcomers to the spec try to fit this ability in until they're comfortable with the flow, if you will, of the spec.
Stat Priorities Accuracy to at least 100%. That is the "safe-zone" when it comes to your Force abilities always hitting the target. Critical Multiplier (Surge) to 75% from Rating (about 325) Critical Chance to around 30% from Rating and Strength (the difference is variable depending on how much strength you have) Strength > Power.
Combat:
Spoiler
The Combat spec is all about hitting your target as hard and as frequently as possible. Ataru Form is the foundation and centerpiece of this spec as it directly affects 5 of the 17 talents in the Combat tree. The way the tree works out is to make sure that you have Combat Trance procced when you use Blade Storm preferably while the buff from Precision Slash is up, making your Blade Storm critically hit and completely ignore armor. Blade Rush helps ensure that the Combat Trance proc is up by automatically proccing the extra damage from Ataru Form. Zen also provides extra burst when used in Ataru Form because it allows you to get Blade Rush off six times in six seconds (depending on latency and the amount of focus you have) for relatively no cost, and when Blade Rush is used in conjunction with Precision Slash it hits, for lack of a better term, hard. But lets not forget Master Strike because by it's self it does a large amount of damage, but when used with Precision Slash it can hit for 30-50% more.
If you hadn't grasped it yet, Precision Slash, is really important and should be used all the time, but I'm not at the priorities part yet.
A good spec for Sentinels with a few points to spare is 05/31/2 as it includes all the necessary damage, utility and survivability talents required to be successful, while still giving you the ability to tweak your build to meet your raid's needs.
For the talents in the Combat Tree that I did not take, Stagger and Debilitation have almost zero usefulness in Ops environments since there is no noticeable benefit to keeping Trash mob or Add that spawns during a boss fight in place for a second longer. The same essentially applies to Displacement because there simply aren't enough situations where snaring an Add or Trash mob is required in raids and that there will rarely be a time when an encounter will necessitate the use of Pacify outside of melee range.
Optional Talents Insight:: Insight is nice but almost unnecessary in Combat spec because your only Force ability is Blade Storm which ideally should only be used when Combat Trance has been procced.
Swelling Winds: This for fights where extra AoE is desired, namely the Trandoshan phase of Kephess.
Another little tidbit is that if you are comfortable with the Combat spec, I have noticed that I have gotten a DPS gain when I used Cauterize off cooldown, ideally after a Precision Slash cycle, so that you don't risk Combat Trance falling off before your next Blade Storm. I don't recommend trying this for someone who has just picked up the spec.
Stat Priorities Accuracy to at least 100%, the Combat Tree provides 6% accuracy just from Talents and being in the correct form. Critical Multiplier (Surge) to 75% from Rating (about 325) Critical Chance to around 30% from Rating and Strength (the difference is variable depending on how much strength you have) Strength > Power.
Defensive Cooldowns/ Abilities:
Spoiler
Force Camouflage: This is your aggro dump, it also puts you in a temporary stealth, reduces damage taken by 50% and increases movement speed by 30% for 4 seconds. Usually, save it for if and when you pull aggro, for Sentinels it's usually within the first 10-15% of a Boss fight unless your tank is really on top of his game, otherwise it can be used when you have to navigate through areas of heavy AoE damage (like Gift of the Masters on Kephess).
Rebuke: Six seconds of 20% reduced damage that refreshes the duration once every three seconds for up to 30 seconds. It also reciprocates a little bit of damage once every 1.5 seconds each time you take damage. Now, I realize that this is all in the description, but I wanted to emphasize how amazing this cooldown is when it can be used every 60 seconds. It has a potential 50% up-time, making it easily the best defensive in the game. Use this when you expect to take AoE damage from bosses, Gharj's and Toth's stomps namely, also good for the trandoshans during the "Shield Phase" of Firebrand and Stormcaller.
Saber Ward: A very powerful defensive cooldown as it not only increases your chance to avoid Kinetic and Energy based attacks, it also reduces incoming Tech and Force damage (this includes attacks like Lightning and Tracer Missile as well as Elemental (Burns) and Internal (Bleeds) damage). Use in situations such as Toth's Berserk, Gharj's Frenzy, or when your tank is down and waiting for a Battle Rez.
Guarded by the Force: This is the very last defensive you should ever use, and only when the **** has completely hit the fan, you're one of the last people up and you're sure you can kill the boss within the five second duration. While the 99% damage reduction is very nice, the cost of 50% of your current health prevents it from being used frequently. When you do use it, I would advise that you use a medpac if you haven't used it already during the fight.
Transcendence: A great ops-wide mobility buff that is best used in situations such as Gift of the Masters on Kephess and Gharj's Frenzy platform switches in EV. The only prohibiting factor of this ability is that it requires 30 stacks of Centering, but that is easily placated with the use of Valorous Call.
Additional Rating Information
Spoiler
In regards to the suggested stats there are a few things I should mention those are simply baseline suggestions. The people that are much better at applied math than me figured all these ratings and stats out and the details are as follows.
Augments:Without question use Strength augments over Power. Having 14 Strength Augments as opposed to 14 Power augments translates to a loss of like 5-7 raw damage, but an increase of about 1% Critical Strike Chance. The difference is really minute, but Strength gives a better all around benefit (damage and crit) than Power.
Now, if you're wondering which of the four ratings (Accuracy, Surge, Crit and Power) are the most important then I've got an answer for you. Neither. This is because none of the talent trees have anything that improves DPS from a Crit proc, nothing specifically requires certain levels of Surge or Accuracy, and Power is just the wonder boy rating improving damage across the board. On to specifics.
Accuracy and Surge:These two ratings are roughly 1:1. One point of Accuracy is worth one point of Surge. That said Accuracy beyond 100% is your gear budget being wasted. After 100% Accuracy you should shoot for Enhancements that have Surge on them, the reason being is that while Surge does start to hit it's Soft cap at around 75% it doesn't stop adding to your DPS.
Crit and PowerCrit and Power are roughly 1:1 as well. After an extensive bout of like 40 different parses it has been determined that the difference in DPS with 164 Critical Strike Rating and 328 Critical Strike Rating is within 1% for both Combat and Watchmen (Focus wasn't tested on the account of it being the red headed step-child that doesn't compete with Combat or Watchmen in terms of DPS) when exchanged with Power. Simply put. within a reasonable extent, it doesn't matter how much Crit rating you have so long as you offset it with Power.
A few gearing and modification tips.
Armorings/ Hilts: Always go for the Strength heavy armorings and hilts. Always.
Mods: When looking to increase your overall damage the mods you should use are the Deft Mods (just plain 25, 26 and 27) and the Potent mods.
Enhancements: Each enhancement should be the 27 End/ 41 Rating A/ 57 Rating B and their counterparts depending on which of the Secondary stats you're working on.
Basically what I'm getting at here is that if your mods have more Endurance than Strength or Secondary Stats you're wrong and should feel bad.
In the Event that Torhead's talent calc is bugged, here are the links to the builds I've posted from another calc.