O9S – Chaos

Encounter Overview

O9S – Chaos expands significantly on the normal version by removing telegraphs, adding debuff-driven mechanics, and requiring strict execution during overlapping sequences. The fight is built around four major segments, alternating between elemental phases and a central DPS check.

The opening mechanic determines the order of elemental phases, making early recognition critical for predicting the fight timeline and preparing positioning assignments.

Dungeons Trials Raids

Relic Weapons Relic Armor

For a full breakdown of raid difficulty across all tiers, see the FFXIV Raid Rankings.

Arena Overview

The encounter takes place on a square arena with no barriers, making knockbacks lethal if mispositioned. Many mechanics require intentional knockback usage or precise positioning relative to the arena edges.

Elemental phases modify the arena, restricting safe zones and forcing controlled movement patterns across limited space.

Boss Mechanics

Core Mechanics (No Telegraphs)

Latitudinal / Longitudinal Implosion: Sequential directional AoEs with no telegraph. First resolve initial cones, then immediately rotate into the previously hit zones. Getting hit applies vulnerability and is often fatal on repeat failures.

Damning Edict: Untelegraphed 180° cleave. Players must react instantly and move behind the boss—this also determines phase order.

Chaotic Dispersion: Tankbuster with Physical Vulnerability. Requires a tank swap every cast.

Umbra Smash: Proximity jump to the farthest point. The raid should move away early, then reposition quickly behind Chaos for the follow-up cleave.

Fiendish Orbs: Tethers that deal heavy damage. Tanks should intercept and mitigate to reduce raid pressure.

Big Bang: Large AoE explosions at previous Knock Down locations. Always track where stacks/proximity markers resolved and vacate those areas.

Inferno Phase

Inferno: Central safe zone only. Everyone must stay inside while resolving overlapping mechanics.

Entropy: Sequential explosions (supports first, DPS second). Tanks/healers spread to edges first, DPS stack center, then swap roles. This avoids overlap in tight space.

Implosions + Entropy Overlap: Resolve directional AoEs first, then move to assigned positions for debuff detonation.

Knock Down (Stacks): Tanks/healers receive stack markers. Each must be paired with a DPS—pre-assign positions to avoid confusion.

Big Bang Follow-up: Immediately collapse center after stacks resolve to avoid explosions.

Dancing Orbs: Line AoEs from intercardinals. Maintain movement discipline while finishing the phase.

Cyclone Phase

Cyclone: Central tornado hazard plus directional debuffs.

Headwind / Tailwind: Tanks/healers face away, DPS face toward the tornado. These determine knockback direction and must be resolved correctly.

Tornado Knockback: Used intentionally to cleanse debuffs. Incorrect facing results in lethal displacement off the arena.

Damning Edict + Knockback: Players must use knockback positioning to land safely behind the boss rather than manually moving.

Healer Proximity Markers: Healers move to opposite corners while the raid stacks elsewhere. After detonation, immediately move away from Big Bang zones.

Fiendish Orbs: Tanks grab tethers again—damage spikes here can be high.

Tsunami Phase

Tsunami: Restricts arena to a narrow central strip.

Dynamic Fluid: Donut AoEs resolve in sequence. Entire raid stacks tightly to share safe space.

Umbra Smash + Edict: Movement check—remain stacked, then rotate behind boss together.

Healer Proximity Markers: Healers split north/south while group remains centered.

Big Bang + Donut Overlap: Requires fast repositioning back to center—timing is tight.

Fiendish Orbs: Tanks intercept tethers again.

Earthquake Phase

Earthquake: Applies role-based debuffs and removes southern safe space.

Accretion (Supports): Must be healed to full before expiration or death occurs.

Primordial Crust (DPS): Must take lethal damage to cleanse (leaves them at 1 HP instead).

Landslide: Knockback toward unsafe zone. Pre-position north edge.

Implosions (DPS soak): DPS intentionally get hit twice to cleanse debuff. Supports must avoid entirely.

Stack Markers + Knockback: Tanks/healers pair with DPS and spread along north edge.

Big Bang: DPS intentionally “die” here to cleanse, while supports avoid.

Dancing Orbs: Final movement pressure before phase ends.

Bowels of Agony (DPS Check Phase)

Bowels of Agony: Reduces all players to 1 HP and applies overlapping debuffs.

Orb of Chaos: DPS check—must be destroyed before gauge fills.

Debuff Resolution:

• Tanks/healers cleanse Headwind via knockback from DPS Entropy
• DPS cleanse Primordial Crust by being hit by Dynamic Fluid

Players should pre-assign pairings (support + DPS) and spread evenly around the arena to resolve cleanly.

Enrage Phase

Chaos casts all elemental abilities in sequence with no resolution windows.

Debuffs become impossible to cleanse, leading to a guaranteed wipe if the boss is not defeated in time.

Encounter Flow

The fight begins with either Damning Edict or Implosions, determining the order of elemental phases.

Players resolve two elemental phases, complete Bowels of Agony, then handle the remaining two phases before entering enrage.

Success depends on early recognition, disciplined positioning, and clean execution of debuff-based mechanics.