JP Boss Guide by /u/Zurai001

Multiplayer Enemy AI by /u/TFMurphy

BOSS: Soul Cage (IX)

Difficulties: 160 (Ultimate ) and 220 (Apocalypse )

Mastery Conditions:

• Win with 4 or more party members alive.
• Reduce Soul Cage's ATK.
• Reduce Soul Cage's MAG.

Overview:

• Has three movesets based on three different states.
• In his standard state, he uses a lot of powerful AoE ranged physical. Some of them include Shockwave (ranged physical to either single target or all characters), Leaf Swirl (heavy ranged AoE physical damage to the party) and Ultimate: Leaf Swirl (heavy piercing ranged AoE physical damage to the party). He has access to one magic attack in this phase, which is Fira (heavy AoE Fire-elemental magic damage to all characters).
• If he is hit with a Fire-elemental attack, he enters Burning state. In Burning state, Leaf Swirl and Ultimate: Leaf Swirl are changed out for Flame Blades (heavy ranged AoE Fire-elemental physical damage) and Ultimate: Flame Blades (heavy ranged AoE Fire-elemental physical damage, reduces all characters' Fire-elemental resistance for a period of time). While he still has Fira, he also gains access to Firaga which is a stronger variant of Fira.
• If he is hit with a Fire-elemental attack while in Burning state, he enters Burning (Strong) state. In Burning (Strong) state all he does is spam Ultimate: Firaga, which does heavy piercing overflow Fire-elemental magic damage to the whole party.
• Every 8 turns where possible, Soul Cage will cast Fira on himself. He also has special immunity to Reflect.
• In his weaker phases, he gains Counter Fira, which he will cast on himself to set himself on fire. Triggers off physical attacks only.
• Lastly, if he is hit with an Ice or Water-elemental attack while in either Burning or Burning (Strong) state, he will revert to his standard state.
• Soul Cage is weak to Holy. Resists everything else. In standard state, he is weak to Fire. In Burning state, he resists Fire, and in Burning (Strong) state, he absorbs Fire. The guide Zurai linked doesn't mention it, but I believe Soul Cage should be weak to Ice and Water in either Burning states.

Tips:

• Ensure you have an Ice/Water-elemental ability ready for whenever he sets himself on fire. You do not want to let him enter Burning (Strong) state.
• Not much to worry about on the status effects front of things (low chance to Stun, high chance to Sap). Focus on Fire-elemental resistance where possible.
• Lean more towards physical mitigation for this fight. The likes of Lion and Irvine are great for this fight with their BSB's, though note that Irvine's BSB has Fire-elemental attached to it, so be prepared to douse him immediately after.
• Special mention goes to Celes' and Delita's BSB. Both of them have an Ice/Holy-elemental command, which not only hits Soul Cage for weakness every time, but can also douse his fires at the same time should he be set on fire at all.