At health percentages, the Herald assaults the players' minds, pulling them deeper into realms of insanity. While players are in these insanity realms, they continually gain stacks of [Hysteria]
. The further they dive into these realms, the faster it stacks.
Each realm employs its own method of assaulting players' minds. Within the fear realm, players continually spawn Horrific Visions from [Manifest Nightmares]
. Within the delirium realm, everyone becomes hostile but has their haste increased.
After all realms have opened, Za'qul gains empowered versions of his abilities that allow the players to move between realms in order to combat his mechanics.