How to access:
Clear all of the Lost Chapter stages in Normal mode (no need to get a full Complete on everything at first) to unlock their Hard versions. This will give you access to the Hard (CHAOS) version of the last boss fight.
Stage Difficulty: Level 180 (CHAOS)
Mission Requirements:
Score 560k |Clear without any KOs | Clear within 105 turns | Take 15000 or less HP damage
Boosted Characters: Cinque, Snow, Cait Sith
Various team options with and without boosted characters are available in this event’s Call to Arms!
Fight Overview
This fight marks a significant jump in difficulty after the previous few Chaos. Both waves are dangerous and require some planning on how to deal with their specific mechanics. Most magic damage dealers are not recommended here, because enemies the first wave counter BRV magic attacks and the last wave reduces magic damage by 90% (but you can bypass that with Element Resist Down abilities). Fire is also resisted in the first wave, while all enemies are weak to Ice. The boss in the last wave resist Paralyze and MAX HP Down, but other than that, debuffers work very well here. For an easier fight, you can bring a good tank, supports with strong healing or damage mitigation, and a physical attacker with the ability to delay or blind the target.
The best summon choice here is Shiva; and not only for the elemental advantage against both waves. All enemies can buff their own speed and have dangerous attacks. Shiva’s speed bonus allows your team to keep up.
Wave 1: Marilith x2
| Sword Dance |    attack |
| Cross Blade |  attack |
| Absolute Chaos | attack; inflicts  3T Poison,  3T MAX HP Down, 3T MAX BRV Down on target |
| Raining Swords | increases BRV;  attack + attack |
| Mustard Bomb |  attack + attack;inflicts  3T Resist Down on target |
| Counter Firaga | Counters Magic BRV attacks; attack |
| Roiling Flames | Grants  3T ATK Up, 3T SPD Up, 3T Enchant to self |
Sword sharpened!: Raises ATK, DEF, SPD, INT BRV, MAX BRV (activates at 80% HP)
Sword further sharpened!: Raises ATK, DEF, SPD, INT BRV, MAX BRV (activates at 50% HP)
Enrage: No. They do not power up when one is defeated, except for Raining Swords when killed (see detailed explanation below)
The first wave brings a pair of Mariliths who mostly focus on single target Melee attacks, of which the most dangerous (and used annoyingly often) is Absolute Chaos. It applies some nasty debuffs, especially the painful 3T MAX HP Down. If a non-boosted character is hit by it, the follow-up attack from the other Marilith could cause a surprise death. If you have a tank to keep them target locked, it will protect your other team members from those debuffs. If that tank is Galuf, you can completely ignore the debuffs due to his evasion; Warrior of Light’s debuff evasion is slightly less reliable, but still helps.
The Mariliths are fast and can buff their own speed and damage even further with Roiling Flames, so take them as a serious threat. Their most damaging attack is Raining Swords, which combines a BRV gain into a group BRV + HP attack. It almost always hurts, and will cause some SERIOUS damage if anyone in your team is broken by it. It can be very hard to deal with these attacks if both Mariliths do them back to back. A good way to avoid this is to focus your breaks/delays on only one of them. This will cause them to go “out of sync”, using different attacks instead of comboing the same attack simultaneously.
Note: these Mariliths do not have any special resistance to magic, but if they are hit by a magic attack that causes damage only, they will retaliate with Counter Firaga. A Marilith will not counter if she takes damage from the magic attack.
The worst trick up their sleeve is that whenever a Marilith dies, it will unleash a Raining Swords attack before disappearing. If you kill both at once, that’s an almost guaranteed game over. So the main hurdle of this wave is finding a way to kill them without being shredded by this counterattack.
Tools to deal with the Death Throes Raining Swords gimmick:
-> Summon: If the Mariliths die while your Summon is in effect, there will be no counterattack. This is the most accessible option, as it can be used by any team. The downside is that it forces you to spend the summon on the first wave, while it could be very helpful against the second; and it requires that both Mariliths be killed within that 6-turn window. Since they do not enrage when one dies, the battle could be easier by focusing one of them down first (if you can use one of the other methods below).
Suggested units: Any
-> Launching: Killing a Marilith during a launch will not trigger the counter. If you have a character who can initiate launches on demand, this is a great option and allows you to focus one of the enemies first, making the other much easier to deal with.
Suggested units: Cinque, Cecil (Dark Knight), Tifa, Noctis
-> Paralyze/Silence/Freeze: If the Marilith is afflicted with one of these debilitating conditions that prevent them from acting or from causing HP damage, the counter attack will not be a danger.
Suggested units: Setzer, Agrias, Exdeath
-> HP damage reduction/immunity: If you can nullify or severely reduce the HP damage dealt by the attack, you can kill them safely.
Suggested units: Porom, Hope, Basch, Beatrix
-> Shields: A good shield can absorb the BRV portion of the attack and make sure the amount of damage you take is survivable.
Suggested units: Warrior of Light (preferably with a support to boost his INT BRV, like Aerith or Selphie)
-> Evasion/Last Stand/Blind: Edge has the singular ability to make the whole team evade the counterattack if it happens while the buff from his EX skill is up. Other characters can evade the attack, survive it with 1 HP (“Last Stand” style passives), or give it a chance to miss entirely. Not as reliable as the previous options, though.
Suggested units: Edge, Eight, Y’shtola, Aerith, Galuf, Shadow, Wakka
The Big Cheese: The Mariliths are not immune to their own MAX HP Down debuff. Yuffie has the singular ability to yeet that status right back at them, cutting their HP in half just like that. If you deal enough damage before the debuff expires, this wave becomes much shorter (but you will still have to deal with their counterattacks upon death if they don’t die during a summon). Here are video examples with Yuffie in your main team and Yuffie as a friend unit.
Wave 2: Bastion Giant
| Punch | attack |
| Gigant Punch | attack; higher turn rate when inflicting Break or attacking Broken target |
| Wallop | recovers from Break; attack; |
| Magic Bullet | attack; inflicts 3T INT BRV Down, 3T ATK Down on target |
| Fragment | attack; |
| Particle Distribution | attack; increases BRV; inflicts 3T DEF Down on all targets |
| Acoustic Pressure Wave | increases BRV if less than INT BRV; attack |
| Drumming War | attack; inflicts 3T SPD Down on target;high turn rate |
| Ascension Strike | attack; increases BRV; grants 3T ATK Up, 3T SPD Up to self |
Movement becomes lighter: Raises ATK, DEF, SPD, INT BRV, MAX BRV (activates at 80% HP)
Movement becomes even lighter: Raises ATK, DEF, SPD, INT BRV, MAX BRV (activates at 50% HP)
The last wave of this fight feels like fighting a surprisingly nimble brick wall. Whenever the Bastion Giant acts, it will use a combo of attacks. While over 50% HP, it does 2 attacks in a row. Under 50%, it’s 3 attacks per turn. They all count as a single turn for effect of buff/debuff durations, counter attacks, delays, etc. If it is targeting a single party member, all attacks will hit the same person. If it queues an attack, it will be a sequence of attacks.
This enemy has immense attack power. You do not want to be broken by its attacks, as it has high turn rate on some of its abilities and surviving two combo attacks in a row is very hard for parties without defensive abilities. When it reaches 50% HP or less, the fight becomes extremely dangerous without a tank to withstand its barrage, or strong damage mitigation to survive his HP attacks.
The best defense against this is to not let the Bastion act at all. Characters who can lower its speed or turn rate certainly help. But the real stars of the show are delayers. If you can make it to 50% of its life bar, it is the perfect time to call in that Leo friend and spam Master Blade until you can’t even see the enemy’s portrait in the turn order. If you still have your Summon available, even better; use it first before starting the delay spam, or save it as a last resort for when the boss catches up with you.
If you don’t have a good delayer in your own team, make sure you have other ways to survive the second half of this wave, like a tank, evasion, Blind, or other ways to nullify its damage. The Bastion Giant does not have many tricks up its rocky sleeves, but if you can’t deal with its brute force, death will be swift.