Sightless Eye
Drops from Rezira the Seer. I am willing to bet this item will get nerfed soon; "A buff longer than the CD? Can't have that!" *Gives it a 2 hour CD* "Fun was detected!" ~ Blizzard
The Sightless Eye is a toy that drops from Rezira the Seer in Antoran Wastes and can be purchased from NPC vendors, granting invisibility that persists while mounted or shapeshifted but breaks upon taking damage or casting damaging spells.
Guide awaiting review
Locate Rezira the Seer
Travel to Antoran Wastes and find Rezira the Seer at 65.0, 82.4 to farm the toy as a drop.
Use Observer's Locus Resonator
If you have 
, use it to portal to Rezira the Seer's location, which other party members can also use.
Defeat or loot Rezira
Defeat Rezira the Seer to obtain the Sightless Eye toy as a drop.
Alternative: Purchase from vendor
If farming is not viable, purchase the toy directly from NPC vendors Rezira the Seer or Horos.
Tips
The invisibility effect works while mounted or shapeshifted, making it excellent for gathering and archaeology at dig sites where you can approach NPCs without triggering aggro.
The buff breaks upon taking any damage, including fall damage, or when casting damaging spells, so use it only when traveling safely or gathering.
