Aranea has 10,000,000 HP and a vast array of Physical Attacks, which grow in power as the battle drags on or the less HP she has. The battle is divided in phases which determine her actions. She can attack up to 10 times per turn.
She is vulnerable to all Stat Breaks, immune to status ailments and has no elemental weaknesses or resistances.
Takes place between 100-50% of her HP. Every action she performs follows a checklist of being any of these actions: Forward Lunge (20% chance) or Dash Thrust (25% chance) or Brandish (x3) (15% chance) or Roundhouse Kick (15%).
Forward Lunge inflicts Physical Damage x3.3 to all units. Dash Thrust is the same x3.8. Brandish is the same but x3 and Roundhouse kick is x3.4 damage to one unit.
After using any combination of Forward Lunge and Dash Thrust that sums 4, she will use Overclock which starts with a x2 modifier but doubles each time used reaching x16.
Every 3 turns while below 60% HP she will use Spectral Flight which allows her to avoid 2 Physical Attacks for 5 turns.
Every 4 turns she uses Wind Reader which boosts her ATK by 50%. This is followed by Highwind the next turn which deals x7.5 damage to all units. However if a Limit Burst (damage or non-damage) is used, the Highwind employed will be a mere x2 only.
This phase lasts between 49%-30% HP. Aranea will use Radical Belief every turn which inflicts x2 damage to one unit and boosts 40% ATK to herself. Wind Reader and Spectral Flight are also used as stated above.
Her attacks now have the following checklist: Dash Thrust (25% chance) or Brandish (x3.5) (15% chance) Smash (30% chance) or Swooping Blow (40% chance).
Her Brandish changes to x3.5, Smash inflicts x4 damage and debuffs DEF by 50% for 2 turns to one unit. Swooping Blow is the same but reduces ATK instead.
The Overclock now triggers on Dash Thrust count only, but it maintained from whatever point it was left since the first phase.
This is the last phase used from 29%-0% HP. Wind Reader is no longer used. Her actions are the same as in Phase 2. However she has a 15% chance once every turn of using a Highwind with x4.8 potency.
Aranea relies purely on brutal Physical Damage to attack the player, as such a Physical Cover Tank geared with high HP, DEF or Evasion should minimize the difficulty. If the Tank in question has full evasion then the battle will not be lost. Otherwise the Tank must be resilient enough to resist Aranea's brutal attacks. Veritas of the Earth is an excellent choice as the Earthlord can protect all units with Guardian and can reach high HP and DEF and can prevent stat breaks with Omni Block. He's also a great Counter Tank which will fill Limit Burst and Esper Gauges pretty easily and even get rid of Spectral Flight as he counters. The only setback is that the series of Counters may drag on for very long but otherwise is an effective choice.
Debuffs will also be needed to decrease her ATK as her modifiers are very high so even a sturdy Tank can be destroyed without supportive measures, including buffs as well. Warrior of Light is not recommended for this role at least the first turn so as to not prevent him from Covering allies. Veritas of the Dark, Kryla, 9S or other debuffers which can decrease ATK and possibly so her DEF (if using Physical Damage units) should be used. Using Magic Damage is also viable since it won't be subject to the ATK breaks, in which case her ATK and SPR should be debuffed.
The player should bring healers too. Garnet can be helpful now that she can be upgraded at full rarity, as she can easily fill the Esper Gauge and provide heals if needed. She also gets enhanced Esper Damage so if required the player can cap a chain with an Esper (preferably Bahamut or Leviathan) for massive damage against Aranea.
Buffers used should include Soleil, Lunera, Ramza or Roy for maximum benefits. Damage reduction also works if one wants to prioritize protection vs overall damage too.
The player should be wary of Wind Reader and Radical Belief, the former if unchecked can destroy parties with Highwind so a Limit Burst must be used, while the latter can lead to a less disastrous but still dangerous outcome.
The player should aim to defeat Aranea as soon as possible or Overclock will become extremely dangerous.