Reliably know when currently invisible with:
• Shroud of Concealment (Rogue)
• Potion of the Hidden Spirit (Potion)
• Dimensional Shifter (Engineering belt)
• Wo Relic (9.2 M+ seasonal affix)
• Camouflage (Hunter)
• Greater Invisibility (Mage)
Also shows alert when Engineer belt FAILS to invis.