These guides are only released at least one day after the event has launched, because they are based on first-hand experience from testing and beating the fight with different team comps and strategies. And that takes a good amount of time!
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Fight Overview & Team building
Mission Requirements:
Score 950k | Clear without any KOs | Clear within 100 turns | Take 15000 or less HP damage
Featured Characters: Gladiolus, Kuja, Gau, Vayne, Sabin
Many team ideas with and without boosted characters are available in this event’s Call to Arms!
Recommended:
- A Tank, Healer and/or HP Damage Mitigator to survive their recast and the Orb – but remember they are immune to Target Lock.
Avoid:
- Characters who rely on debuffs with limited uses, because the bosses cleanse frequently. Make sure you can reapply vital debuffs as needed.
Summon tips:
- Leviathan is great to make the bosses act less often (and use fewer recasts), and because its framed buff leaves one less slot open for debuffs; Bahamut is also a good option to lower their ATK.
- The summon is best used when the bosses are in red mode (below 40% HP).
Wave 1: Optimus x2
Base stats (courtesy of DissidiaDB):
Max HP: 5,000,000 | INT BRV: 4500 | MAX BRV: 55000 | ATK: 17000 | DEF: 16500 | SPD: 35 | Chase value: 40
Destructive Laser | Recast ability; removes own debuffs (frames excluded); recovers from Break; guaranteed hit    attack +  attack;inflicts  5T ATK Down, 5T DEF Down, 5T SPD Down, 5T INT BRV Down, 5T MAX BRV Down,  5T Poison;low turn rate |
| BRV Attack |  attack |
| Laser | attack |
| Splash Cannon |  attack;increases turn rate when inflicting Break |
| Flare | attack |
| Knocking |  attack |
| Meteor |  attack;higher turn rate when inflicting Break or attacking target afflicted with Break |
| Breeze Out | recovers from Break;  attack + attack |
| All Gatlings | recovers from Break; attack + attack |
| Full Salvo | increases :brv:; attack + attack |
| Flamethrower |  attack;grants  3T ATK Up, 3T Critical Hit Rate Up to self |
Enrage: No. But beware that both will enter the Red phase together as soon as one falls below 40% HP.
1% HP: 50,000
Dealing with the bosses:
These bosses have three phases, clearly marked by the color of the light at the center of their body. Both change phase together as soon as one of them falls below that HP threshold.
- Blue Light: Starting phase. Will use mainly single target BRV attacks and Meteor (also just a BRV attack). As long as you keep their BRV down, the only dangerous HP attacks will be from the Orb or the recast ability.
- Green Light (<70%): Will become more aggressive and start using BRV + HP attacks, marked in green on their move list above.
- Red Light (<40%): Will also add Flamethrower to their frequently used moves and, more importantly, they will start gaining ~41k BRV after every attack. This is the phase where you wan to burn them down as quickly as possible, and summon or friend can be really helpful to deny their turns.
Regardless of phase, they will constantly charge their recast bar to use Destructive Laser. It is a very hard hitting single target attack, and will replace any non-framed buffs on the targeted character with generic buffs instead. Making it worse, this is a guaranteed hit, and cleanses every debuff from the Optimus before firing. To see this attack less often, avoid taking breaks and try to delay or slow down the enemies if you can.
Counterattacks help a lot to shave down the BRV they gain during the red phase. If you bring Gladio and/or Gau, they will help immensely. Otherwise, guaranteed breaks or enchant/imperil to increase your damage will be good ways to do it. Summoning or using an Amidatelion friend to delete their turns can also give you breathing room to finish the fight before it gets out of control.
Dealing with the orb:
Special: Lowers your team’s INT BRV while the orb countdown is active.
Appearances: when the bosses fall under 80% HP, 50% HP and 40% HP
Countdown: Starts at 8; -1 when player acts, -2 when that boss acts.
Increase/Pause: nothing can stop the countdown, you have to survive the attack.
Orb Attack: Destructive Laser+
cleanses own debuffs (frames included);
increases own BRV;
attack + attack on the character with the lowest current HP
You cannot stop this Orb attack from happening, so you have to bring a way to survive it.
Good characters who can deal with the Orb for you:
- Gladio: completely nullifies the attack, as long as you have his Blink buff up; time LD uses to make sure he covers your team.
- Ardyn: His LD buff will make sure he is always the lowest HP in the team, so all orbs will target him; and they will not be able to kill him.
- Warrior of Light: With his LD buff, you only need to make sure the targeted character has a shield by the time the orb triggers, and the HP damage will be absorbed.
- Porom: She can protect the lowest HP party member with her damage reduction buff, and remove most of the danger from the orb.
- Nine: His LD uses are limited but, coupled with his shields, can be enough to protect everyone from the orb attacks.
- Edward/Eight: you can manipulate their max HP by removing passives to force the enemy to target them (unless someone else takes a big hit right before the orb triggers), and their evasion will make the orb whiff.
🧀 The Cheese Corner
- Gladiolus: It hardly counts as “cheese” when you bring the featured character, since they receive boosted stats and the fight is designed with the intention to make them look good. But it’s worth noting that Gladiolus so effectively neuters the mechanics here, he can duo the Lufenia with Ardyn (shown by ScarletClaire here) or Gau (shown by Xcaliblur here).
DISCLAIMER:
Challenge quests are just a small bonus if you have already geared up the characters it asks for. If you haven’t, it is NOT worth pulling for a new character or spending ingots if you only intend to use them here. You can easily clear it with any team to get 400 gems and 3 tickets. The extra rewards for a Perfect complete with boosted characters are a measly 100 gems and 2% of a BT weapon. Not worth the hassle!
For a good idea of what team comps are able to complete this, and which characters can help without having all their gear, check the Challenge Quest tab in the Call to Arms.