Born in Chaos

Shameless stolen from:  http://www.forcejunkies.com/2011/12/10/the-sith-assassin-codex/

DECEPTION ASSASSINS

"You were deceived."

Playstyle: Spike damage striker, harasser; melee skirmisher.
Mode: Surging Charge
PvE Builds: Armor Piercing (5/33/3), Chain Shock (2/31/8)

Priority List:

    0. Saber Strike (Out of Force)
    1. Assassinate (Target at 30% health or less)
    2. Maul (Exploit Weakness buff about to expire, behind target)
    3. Lacerate (3 or more enemies)
    4. Discharge (Every Cooldown)
    5. Shock (2x Induction buff... so near basically every CD)
    6. Maul (Exploit Weakness just proc'd)
    7. Voltaic Slash or Thrash

Deception is the most martially-based of the three Assassin trees, eventually becoming extremely flashy as a melee combatant. It's the tree the Assassin was built for, and thus levels the most effectively of any Assassin tree early on; where the other trees are grasping for their basics before level 20, the Deceiver already has most of what he needs. It also is unique, as it is the only spec among all 24 Imperial specializations that has no good 30m offensive abilities, and essentially, no method of gap closing beyond Force Speed. In return, it has the most effective control while it is on a target, and the highest damage of any Assassin specialization. The basic conceit of the tree is that you use your martial strikes with a lightsaber to either buy time for your powerful, Force-driven attacks; or that you use those abilities to get into position for a particularly vicious Lightsaber stab in the back.

Since Surging Charge has a chance to activate on each hit, even though it's capped at a maximum of 1 activation per 1.5s, all of your multiple hit moves get more benefit from Surging Charge than it appears. Surging Charge would apparently do similar average damage as Lightning Charge, right? About double the damage and half the activation rate? Think again. Your main two abilities strike twice every period. The chance of at least one activating Lightning Charge is 75%, which is a 50% relative increase from the base activation chance of 50%. However, the chance of at least one activating Surging Charge is 44%, which is a 75% relative increase from the base activation chance of 25%. This difference becomes even more distinct with Saber Strike, which has a 58% chance to activate Surging Charge, and an 88% chance to activate Lightning Charge - relative increases of 130% and 76% respectively.

Incidentally, this means that if you follow the pattern Voltaic Slash, Voltaic Slash, Shock, you will only reliably have one instance of Static Charges saved up. Static Charges gain very slowly. You'd need six or seven full cycles to get a stack of five with high certainty - that's around 30 seconds, and Discharge will be up every 12 to 15 seconds. Some math will have to be done versus reliable gear levels, to show what the optimum amount of Static Charge stacks is to release in a maximum DPS cycle. My suspicion is that Static Charge should be simply considered a bonus rather than a need in a maximum DPS cycle, and that Discharge should only be held back, waiting for a full stack, when in burst damage phases.

Overload and Shock deserve special mention with this tree; their secondary effects are useful to allow you time to go behind the target and stab it. Overload's knockback can even pull this off in PvP; don't expect that effect from Shock in harder PvE or any PvP, however.

PVE

In Player versus Environment content, the Armor Piercing (5/33/3) damage rotation is pretty evident. As with Darkness, it is a very erratic priority list, as the key of the tree has you watching your rotation. The Deceiver is surprisingly good at Area of Effect damage for a single-target specialist, but only in bursts; while it still has the awesome Lacerate, the Deceiver can most efficiently use it when just coming out of stealth, or under the effect of Blackout. For those of you playing along at home, in a group situation, the Infiltrator can get 18 consecutive seconds of vicious, vicious AoE slashy goodness: coming out of stealth, blackout, Force Cloak.

When not being a whirling dervish, the Infiltrator still hits really, really hard. Starting out, you'll find that you like to stab people in the back. It's not as necessary as you think, though. Without the Exploit Weakness buff which comes from your other attacks, Maul typically does not do enough damage for its crippling Force Cost versus the combination of Voltaic Slash or Thrash followed by a Shock. Even under the effects of Dark Embrace, you'll only regenerate enough Force Points for another full-cost Maul about every third GCD.

Entropic Field is not a strictly necessary skill, but it is an advisable one for group content due to the prevalence of PvE splash damage. While leveling, those points can be otherwise assigned. The 2 points in Entropic Field, Fade, Resourcefulness or Avoidance can be moved to any of the slots as you see fit.

The Chain Shock (2/31/8) build has recently been brought to my attention, and on targets which have less armor (below about 20% armor), it looks like it may overtake the Armor Piercing build (which has been renamed from Standard for that reason). This is pending on how much armor reduction enemies are calculated with on average.

GEARING

As with all Inquisitors, Willpower is your primary stat, and you use both physical and Force abilities, so you would rather take the Power statistic rather than Force Power. You do not need Alacrity as none of your abilities of note have cast-times. Critical Strike Rating is your single most important statistic, as your critical hits with Maul, Discharge and Shock do significantly more than the base +50%. While Surge Rating is also nice, you flat-out crave critical strike more than anything else until diminishing returns kicks in hard, because you have no method of ensuring critical strikes to keep Exploitive Strikes up aside from Force Potency.

Surge Rating is still valuable as well, because the built-in diminishing returns on Surge do not account for your flat bonuses to critical from your specialized skills. You can easily sport another +20% critical strike damage from gear.