Avoid all water, especially puddles dropped by elemental adds when they die. Move to the inner most circle and run ahead of the rotating water blast.
DPS only one of either Strife or Peril until it has unhealable stacks (10?) of Intensity, then switch to the other. Blow cooldowns if stacks get too high.
Kill suns, then tank/dps shas, heal/burn through Zao's random damage.
Tank in the middle. Avoid waves of flame and really, really don't stand in green circles on the floor. Dispel the fire DoT ASAP.
Dispel Touch of Nothingness ASAP. Stack and nuke adds with DPS cooldowns during purple phase, or after 40sec they explode and heal the boss.