1.0 - The Assassination Rogue - Level 80 Builds and notes
Assassination is a high burst damage as well as somewhat high sustained DPS build, capable of matching the combat rogue for damage output, just with a little bit more effort due to a more varied selection of attacks. The one downside, if you're not a dagger fan, is that this build requires daggers.

As of the 3.09 patch Mutilate builds are very nice for raiding, PVP, and leveling. The Mutilate skill does require daggers, but there are some very nice daggers available, even off the Auction house. the 3.1 patch doesn't change this tree significantly.

Mutilate takes the importance of poisons to an enhanced level as well as altering the standard rogue rotation away from the staple of sinister strike spam to a more unique combination of finishing strikes and overall style.

This guide is simply intended to provide a general overview of the Assassination Rogue. For a far more in-depth and highly detailed resource on Rogues, including builds, PvP, leveling, raids, etc., check out the Killer Guides' Rogue guide, right here.

2.0 - Talent Builds

54/17/0 Assassination (dagger build, courtesy of Azeroth Now )

51/13/7 Assassination/Mutilate (This is a patch 3.1 build)

Major Glyphs to consider, depending on how you choose to fight:

Eviscerate - adds 10% crit chance
Garrote - more total damage over less time
Slice and Dice - adds time, good for long fights.
Rupture - Adds time = more damage. Not so hot for short fights.
Huunger for Blood - Adds 3% to HfB. This is new for 3.1 so will be rare and expensive for awhile.
2.1 - Attack Rotations. Your Eviscerate and Envenom hits will refresh Slice and Dice to it's full, 5pt, duration.

For long fights:

Garrote
Shiv
Mutilate
4 Point Slice n' dice
Mutilate till 4 combo points
4 Point Rupture
Mutilate till 4 combo points
4 Point Eviscerate
etc. alternating Eviscerate and Rupture
or

Open up with Garrote
Hit Backstab (Shiv if solo)
Then, throughout the fight...
Slice n Dice
Mutilate x2
Envenom
Mutilate x2
Eviscerate
(Repeat)
For Shorter Fights

Cheap Shot
Shiv
Mutilate
Eviscerate
Mutilate until 4 combo points (if it's not already dead)
Eviscerate
In this rotation each mutilate usage will be as many as is required to reach 4 combo points. Look into the Rogue Focus Classic addon to keep track of Energy and Combo Points.
2.2 - 49/15/7 Leveling Assassination Build - (You won't need daggers with this build until you get to Close Quarters Combat.) Use Sinister Strike as your main attack until you get to Mutilate

Cut to the Chase and Hunger for Blood are skipped here as they are both more useful for the long fight youi'll see in raids.

5/5 Malice x5 (more crits)
5/5 Dual wield Specialization x5 (You're using two weapons, right? )
5/5 Precision x5 (help cancel the duel weild hit penalty)
3/5 Close Quarters Combat x5 (more crits)
3/3 Improved Eviscerate
2/2 Opportunity (more damage from your opener)
2/2 Remorseless Attacks x2 (Great for leveling, more crits.)
5/5 Lethality x5 (more burst damage)
5/5 Relentless Strikes (Restores energy)
3/3 Vile Poisons (More poison damage)
2/2 Ruthlessness (Adds combo points)
53 Cold Blood (guarantees a crit on next strike)
2/2 Quick Recovery x2 (heal faster, use less energy when missing)
3/3 Imp. Kidney Shot x3 (more damage)
5/5 Seal Fate x5 (more combo points)
64 Overkill (Use less energy)
3/3 3pts of Improved Poisons (Better chance to apply poison)
3/3 Find Weakness x3 (more overall damage)
2/3 2 pts in Focused Attacks (more energy recovery)
74 Mutilate
3/3 3 in Master Poisoner, for more crit against poisoned targets
78 Last point in Focused Attacks (now 3/3)
3/3 3pts in Puncturing Wounds (+15% Mutilate crit chance)
82 1 pt in Ruthlessness
2/2 Last two in Close Quarters Combat

3.0 - Assassination PvP Build
From AzerothNow: The way this build works is by relying purley on critical chance and doing the most combo move damage possible, while still being able to get away with fleet-footed talent. With this build you also have Cold Blood which will be great in the time of need when you think you are about to get taken down by another rival. You also have Preperation from the Sublety tree so you can use Cold Blood back to back for increased damage to other players.

You will need to start off by Stealthing up to the enemy, opening up with Garrote, then Backstab. After this it would be wise to Kidney Shot the opponent, to lock them up for a few seconds. You could then use Vanish and Cheap Shot to keep the stun going.

Look into Glyphs of...

Eviscerate
Evasion
Sap
41/5/25 This is a very popular Assassination/Mutilate Arena Build, but it also works quite well for leveling. It's Ok in instances, but gives up too much DPS to a full Mut build to be great for raids.

3 in Improved Eviscerate
5 in Malice
3 in Puncturing Wounds
1 in Vigor
5 in Lethality
3 in Vile Poisons
2 in Fleet Footed
Cold Blood
2 in Improved Kidney Shot
2 in Quick Recovery
5 in Seal Fate
2 in Murder
2 in Deadly Brew
Overkill
2 in Find Weakness
Mutilate
5 in Dual Weild Spec
5 in Relentless Strikes
3 in Master of Deception
2 in Opportunity
2 in Dirty Tricks
3 in Camouflage
2 in Elusiveness
3 in Initiative
2 in Heightened Senses
Preparation
2 in Dirty Deeds
 

NOTE: The below section is nearly identical for all three specializations of rogue, this is due to the usage of almost entirely the same stats for any rogue no matter the attack rotation and/or talent build. You can see more stat details on our Rogue Class Guide page.

4.0 - Number Crunching
Agility - 1pt = 1 Attack Power, 0.55 Critical, 2 Armor, 0.95 Dodge Rating
Strength - 1pt = 1 Attack Power
Attack Power- 14 = 1.0 DPS
Critical Rating - 22.1 = 1% Critical

Hit Rating - 15.8 - 1% Hit
Dodge Rating - 18.9 - 1% Dodge
Haste - 15.7 - 1% Haste
Weapon Expertise - 1 - 0.25% lower chance for enemy to dodge/parry

4.1 - Hit Rating, Crit, etc.

Defacto Priority:

Agility - Hit Rating - Attack Power - Critical Rating

What to shoot for when entering Karazhan & Heroics:

Hit Rating: 90+
Attack Power: 1100+
Critical Rating: 23%

Since dual-wielding imposes a hit penalty consider adding more hit rating when you can.

What to shoot for when heading into 25-Raids:

Hit Rating: 200
Attack Power: 1450
Critical Rating: 25%

4.2 - Gems

Green:

Shifting Shadow Draenite - +3 Agility & +4 Stamina
Glinting Flame Spessarite - +3 Agility & +3 Hit Rating

Blue:

Shifting Nightseye - +4 Agility & +6 Stamin
Glinting Noble Topaz - +4 Agility & +4 Hit Ratinga
Relentless Earthstorm Diamond - +12 Agility & 3% Critical Damage

4.3 Enchantments

Head: Glyph of Ferocity +16 Hit & +34 Attack Power
Alternative Head: Glyph of the Outcast
Shoulders: Aldor/Scryer Inscription - +15 Critical & +20 Attack Power OR +10 Critical & +30 Attack Power
Back: Greater Agility - +12 Agility
Chest: Exceptional Stats - +6 all stats
Wrist: Assault - +24 Attack Power
Hands: Assault - +26 Attack Power
Alternative Hands: Superior Agility - +15 Agility
Legs: Cobrahide Leg Armor - +10 Critical & +40 Attack Power
Alternative Legs: Nethercobra Leg Armor - +50 Attack Power & +12 Critical Rating
Feet: Dexterity - +12 Agility
Alternative Feet: Cat's Swiftness - +6 Agility & +8% Run Speed
Weapon: Greater Agility - +20 Agility
Alternative Weapon: Mongoose +120 Agility & Increased Attack Speed Proc

4.4 - Consumables

Superior Healing Potion - Heals 1500 - 2500 Health
Elixir of Major Fortitude - +250 Health & 10 health/5 seconds(For AoE damage/Fights you have difficulty surviving)
Elixir of Major Agility - +35 Agility & +20 Critical Rating
Flask of Relentless Assault - +120 Attack Power

Food:

Spicy Hot Talbuk - +20 Hit Rating & Spirit
Warp Burger - +20 Agility & Spirit

5.0 - PvE Gear Guide
Note: As this is a PvE gear guide I'll only list the PvP rewards capable of being obtained via Honor, arena rewards are however viable alternatives to many pieces of gear.

Many pieces of gear will also be equally useful to both assasination, combat and subtlety - the primary differences being in weaponry as oppposed to the armor which possesses stats all rogues will utilize.

Head:

[Quad Deathblow X44 Goggles] - Crafted
[Deathblow X11 Goggles] - Crafted
[Helm of the Claw]- Quest Reward
[Stealther's Helmet of Second Sight] - Quest Reward

Neck:

[Choker of Vile Intent]- (25) Badges of Justice
[Vindicator's Pendant of Triumph] - PvP Reward
[Bone Chain Necklace] - Heroic Underbog
[Earthen Mark of Razing] - Quest Reward

Shoulders:

[Shoulderpads of the Silvermoon Retainer] - Heroic Magister's Terrace
[Gladiator's Leather Spaulders] - PvP Reward
[Expedition Scout's Epaulets] - Quest Reward
[Mantle of Perenolde] - Old Hillsbrad

Back:

[Dory's Embrace] - (60) Badges of Justice
[Vengeance Wrap] - Crafted BoE
[Cloak of the Coming Night] - Normal Magister's Terrace
[Cloak of the Craft] - World Drop BoE

Chest:

[Tunic of the Dark Hour] - (100) Badges of Justice
[Primalstrike Vest]- Crafted
[Shadowprowler's Chestguard] - Crafted BoE
[Gladiator's Leather Tunic] - PvP Reward

Wrist:

[Master Assassin Wristwraps] - (35) Badges of Justice
[Vindicator's Leather Bracers] - PvP Reward
[Spymistress's Wristguards] - Quest Reward

Hands:

[Trickster's Stickyfingers] - (60) Badges of justice
[Fel Leather Gloves] - Crafted BoE
[Handgrips of Assassination] - Black Morass
[Gloves of the Unbound] - Arcatraz

Belt:

[Belt of the Silent Path] - (75) Badges of Justice
[Belt of Deep Shadow] - Crafted BoE
[Vindicator's Leather Belt] - PvP Reward

Legs:

[Trousers of the Scryers' Retainer] - (100) Badges of Justice
[Fel Leather Leggings] - Crafted BoE
[Leggings of the Betrayed] - Normal Magister's Terrace

Boots:

[Nyn'jah's Tabi Boots] - (60) Badges of Justice
[Fel Leather Boots] - Crafted BoE
[Vindicator's Leather Boots] - PvP Reward
[The Master's Treads] - World Drop BoE

Rings:

[Angelista's Revenge] - (60) Badges of Justice
[Shapeshifter's Signet] - Reputation Reward
[Vindicator's Band of Triumph]- PvP Reward
[Ravenclaw Band] - Sethekk Halls
[Kaylaan's Signet] - Reputation Reward
[Slayer's Mark of the Redemption] - Quest Reward

Trinkets:

[Darkmoon Card: Crusade] - Darkmoon Card Deck
[Shard of Contempt] - Heroic Magister's Terrace
[Bloodlust Brooch] - Vendor(41 Badges of Justice)
[Abacus of Violent Odds] - Drop(Mechanar)
[Hourglass of the Unraveller] - Drop(Black Morass)
[Core of Ar'kelos] - Quest Reward

Main-Hand:

[Gladitor's Shanker] - PvP Reward
[Riftmaker]- Reputation Reward
[Whispering Blade of Slaying] - Shadow Laybrinth
[Illidari-Bane Dagger]- Quest Reward

Off-Hand:

[Gladiator's Shiv] - PvP Reward
[Whispering Blade of Slaying] - Shadow Laybrinth
[Illidari-Bane Dagger]- Quest Reward

Ranged:

[Veteran's Musket] OR [Marksman's Bow] - Reputation Reward
[Felsteel Whisper Knives] - Crafted
[Telescopic Sharprifle] - Mechanar