Ghostly

On completion of the quest Preparations for the Underworld, one gains the effect The Breath of Har'koa for a short while. Thereafter, upon approaching the Altar of Quetz'lun, the character will gain the buff Ghostly.

This is similar to the effect of the Bash'ir Phasing Device, with the world changing to the monotones shown when the character is a ghost. In this form, the character can interact with Quetz'lun's Spirit.