Hiding In Plain Sight

Exodar (Ardaan the Solemn):
You can go to Exodar fastest from Orgrimmar and Mount Hyjal portal, or you can taxi to Moonglade or Duskwood, you can then fly to Ruttheran Village, take the ship to the west on map and go to entrance of Exodar, go inside the tunnel there and into the city.
You can see the target on the map as a star (like rares). First Distract the Crystal Golem to seperate it from the target, be careful because it can oneshot you easy and it's a long annoying ghost run, after that when your target moves away, Blind the Golem and attack your target, interrupt his Call for Help. Attack with all cooldowns, kill fast, Vanish, run away.

Darnassus (Taylenne Sweetsong):
You can use the same ship for going back to Ruttheran Village, use the portal there, pinkish glowing tree root with guards all around, go in stealth so you won't be ganked by guards when you're in Darnassus.
Go to the mark in stealth but watch the patrols. Your target will be in a very crowded place (garden party mode), watch out for Huntress Duskrunner and other patrols, she and others can see stealth and they patrol the area on mounts, attack when they go away from the place. Use Cloak of Shadows and Crimson Vial, since your target and all the crowd are casters, pop all cooldowns, kill fast, Vanish, run away. Don't fly, air patrol may shoot you down. Just go out of city and use Hearthstone.

Ironforge (Corin Twinbellows):
Fastest way to Ironforge for a Horde is Twilight Highlands portal in Orgrimmar, short flight from there, or from Silvermoon portal from Dalaran, just run to the Undercity translocator orb then when you're at outer part of Undercity, mount up and fly to Ironforge.
Watch out for Thief Catcher Thunderbrew, he's the stealth seeing patrol in Ironforge. Corin has a buff named Heavy Armor, reducing Physical Damage taken %99, pickpocketing him gives you a key to remove this armor buff, you can use the key in stealth too and stealth won't be removed, but for still killing him fast, preferrably you have to respec for Shadow or Nature damage, Subtlety or Assassination. Outlaw can also do some damage but it will be short comparably. Both with cooldowns are almost enough to take him out with just spell damage but Subtlety is a bit guaranteed. Use all defensives too, pop cooldowns, apply dots, don't move a lot from the corner, kill and try to escape and vanish, you may have to deal with 1-2 guards, so sapping one may help there. He runs inside so try to stun him before getting more guards, besides he yells for help too, so save the kick and interrupts for that. Do the killing, use your defensives, after that, vanish and escape to Stormwind with tram for next target.

Stormwind (Auctioneer Jaxon):
As we exit the tram from Ironforge, we have two ways to get to our target, either flying low and careful or just walk in stealth, target is at the Trade District Auction House. Rightmost Auctioneer in the building. You have to be super careful about the elite guards who can see stealth and ruin you and force you to run a looong ghost run. Avoid them and go inside AH, kill is pretty easy but place is crowded, so keep Vanish on cooldown again, go back to the target, pop CDs, then use defansives and run out, yes don't just vanish rightaway because it can be ruined by one of those elite guards, just run behind the cheese shop, that place is quite safe for using your HS, so survive the run there, vanish and HS.

Quest is done, go to the Order Hall and get your Raven ^^

PS: Sorry for late update, I started this at PTR then forgot to update <:b

On Corin Twinbellows (the dwarf), pickpocket him to loot the key to his armor, allowing you to strip it off of him.

Quest line for the class mount Shadowblade's Murderous Omen starts at [npc=119259] on Broken Shore after completing Breaching the Tomb with a Rogue.

1. 
   
2. Dread Infiltrators - go to your order hall
3. 
   
4. Hiding In Plain Sight - watch the dialogue and travel to:
   (avoid dying, the next graveyards are far away)
   
   - Exodar: (teleport to Orgrimmar and Hyjal, then fly to /way Darkshore 38 32, pass the sea, take the ship at /way Teldrassil 52.4 89.4 to Azuremyst Isle (West) and enter the tunnel at /way Azuremyst Isle 24.53 49.77. Find the Star, use Blind or Distract on the [npc=118895] (strong elite, dies with Ardaan - according to a comment his death may not be guaranteed, so keep your Vanish ready) and kill [npc=118892].
   
   - Darnassus: leave Exodar through the tunnel (/way 35.45 75.0 Upstairs) and take the ship back to Teldrassil. /way Teldrassil 55.10 88.59 Portal. Find [npc=118891] (be careful, lots of mobs). [spell=235310] is interruptible. Use CDs like Cloak of Shadows.
   
   - Ironforge: teleport to Orgrimmar and Twilight Highlands. Fly to /way Dun Morogh:Eastern 60 33, enter Ironforge and find [npc=118889]. Because of [spell=235614], you should spec Assassination or Subtlety and/or trinkets with spell damage procs. You can use Pick Pocket on Corwin Twinbellows to destroy his damage reduction. [spell=235310] is interruptible.
   
   - Stormwind:
   Way 1: go to /way Ironforge 74.90 51.1 and use the Deeprun Tram to Stormwind. Find [npc=15659] within the auction house.
   Way 2: go to Orgrimmar and use the portal to the Blasted Lands. Fly to /way Stormwind 61.8 73.0 Stormwind Auction House
   - return to your order hall
   
5. 
   

[spell=240982] will be added to your mount collection automatically after turning in the quest.

Other color schemes are obtainable by full skilled artifact weapons (Power Ascended):

• 
  
• Assassination: [item=143491]
• 
  
• Outlaw: [item=143490]
• 
  
• Subtlety: [item=143492]
• 
  

They are purchasable from [npc=121282] for 1000 [currency=1220] each.