Chatizad - Clear all trash first. Killing the 2 strathbone guardians spawns the named. If attacked, he starts walking along the spiral pattern on the floor to the next room. Defeat him before he wanders to the portal in the second room or instant death. Gains buff that intercepts all damage when near one of his spawned guardian adds. Best strategy: one offtanks the adds at a location away from the named, the other one kills the named.
Zannaska - Same as first boss. Killing the 2 strathbone wardens spawns the named. Defeat her before she wanders to the portal in the third room or instant death. Gains ward for 300,000,000 damage when near one of her spawned warden adds. Use same strategy.
Chatizad and Zannaska - The nameds are rooted in the center of the room, and immune to damage, if you get close enough they will melee attack though. Walking into melee range and/or attacking them makes the 'a spectral lord' and 'a spectral acolyte' around the room attackable. Killing all spectral spirits releases one of them from the root, and they run directly at you. Kill it before the spirits respawn, otherwise it resets and you have to kill all the 'a spectral lord' and 'a spectral acolyte' around the room again. Same procedure to release the other named, kill it before the spirits respawn. Killing all the 'a spectral lord' clears Zannaska's debuff, all the 'a spectral acolyte' clears Chatizad's debuff. There's something funny about the blood in the room, standing in it made me take damage, but I just avoided it.
If using a merc, perhaps the best plan is to have the merc attack the named while you keep the adds away.
Zannaska gives you a non removable debuff that you can remove by killing all the spectral lords which apparently instantly repop when she becomes active, see photo:
Arrow indicates spectral lords and debuff details are visible.
