If the restless wraith is up, the High Priest event is spawnable.
The tunnels in which the High Priest resides are behind a locked door, which may only be opened with a Polished Stone Key from the Ixt Hsek Syat encounter.
The High Priest is spawned by killing the five Vrex Invokers located throughout the caves: Vrex Invoker Akello, Vrex Invoker Jahzara, Vrex Invoker Kashka, Vrex Invoker Malik, and Vrex Invoker Raziya. Each Invoker spawns a not-yet-attackable Shade of a Vrex Invoker. After the fifth shade reaches the High Priest's spawnpoint, Nkosi Bakari will spawn. Upon spawning:
High Priest Nkosi Bakari says, 'My brothers and sisters, I have heard your calls and I have come. If what you say is true, our children have turned their backs upon Trushar and in doing so have invited evil upon our land. We must cleanse this place and restore belief to our people!'
Upon aggroing the event, the five shades will each cast an unresistable 3-minute charm on their targets. The shades will need to be offtanked.
Each time the High Priest reaches 50% health, you will see:
Shade of a Vrex Invoker says 'High Priest, may my everlasting soul provide you with the strength to cleanse this temple!'
Shade of a Vrex Invoker dissolves into tendrils of ghostly vapor that reach out and replenish the strength of High Priest Nkosi Bakari.
...And one of the shades will be absorbed into the High Priest, bringing Nkosi back up to 100%. This process repeats itself until all shades are down. Then the High Priest can be killed.
High Priest Nkosi Bakari has no special attacks besides his AE (no flurry; no rampage). He does sometimes enrage, however.
Barrier of Serenity
Bow of the Whispering Wind
Bulwark of Living Stone
Caduceus of Retribution
Jade Effigy of Trushar
Jade Inlaid Key
Lute of False Worship
Mask of Eternity
Ring of Celestial Harmony
Staff of Revealed Secrets
Verge of the Mindless Servant
Wand Harness