The "Gnomish Cloaking Device" completely breaks you from combat when used - it's the engineer's Vanish or Shadowmeld and can be used to survive wipes, drop aggro, and leave combat.
The Gnomish Cloaking Device used to NOT break combat/lose aggro (it was previously useless) - but it was changed in an undocumented patch so not a lot of people know about it, which is why the device has been forgotten.
It requires 200 Engineering to use and the Limited Supply item is sold by Zan Shivsproket in the basement of Ravenholdt Manor. (Recipe sells for 15-25G on the AH by the way.)
What few people know, though, is that it allows for a new Rogue strategy: Keeping your normal stunlock rotation even if the target uses a PVP Trinket in the opening CS/KS moves!
You see, once the Cloaking Device breaks you from combat you are invisible for 10 seconds. During this time, you can refresh the duration another 18 seconds by popping an Invisibility pot (which can't be used while you are IN comat) OR simply go back into Stealth, re-equip gear, and then re-open with Cheap Shot. =]
This works great in PVP and I have tested many times with great success (and to their surprise). It's like having 2 Vanish skills available (or 3 with Preparation.)
- Druids can also activate the Cloaking Device, jump back into Prowl mode (immediately or within 10 seconds before the Invisibility wears off) and re-open with their standard attack rotation.
- Mages: Extra long Invisibility. 20s + 10s (w/ Glyph) + 10s Engineering trink + 15-18 second Invisibility Potion
Disadvantages:
- 1 hour cooldown, can't be used in arenas.
- You have to lose a Trinket slot for this.
- Warlocks can see invisible players if they have the associated buff.
- DOTs break invisibility (use Cloak of Shadows before popping.)
Other than that, this can be used in World PVP/BGs or in serious Duels (ie, for Gold). It catches players off-guard and typically causes a lot of confusion (especially when you "Vanish" 3 times).
Anyhow, it's a balancing act of big disadvantages and big advantages.. I'll leave it up to you to decide.
