The Abyss of Time Boss Guide
This is a guide that will cover all of the bosses throughout Persona 3: The Answer. This game mode is much harder than The Journey and you should be expecting about twice the challenge you faced before. Each fight will require strategy from you or for you to out level it. There aren't nearly as many bosses during this play through as there were during The Journey either, I would say about 1/3 as many.
There's one last thing I would like to say before diving into this guide. At one point way later in the game you're going to be put into a situation where you can only control Aigis and Metis. Once you enter this situation you won't be able to go back and gear Metis or level her up. Coming from someone who didn't use Metis the entire game, this totally screwed me over and I had to load a previous save file and grind Metis properly. I'm giving you this warning now so you don't fall victim to the same thing.
Let's get started with the guide!
Malebolge Bosses
Boss 1 Immortal Gigas - weak to wind // Visceral Maya - use fire on
For these two what you'll want to do is take out the Visceral Mayas first and you can easily do that by using fire. If you have a Persona that uses both Fire and Wind you'll be able to do a decent job knocking down everyone since the Immortal Gigas is weak to wind. Ice is a great way to deal damage to everyone too, if you have High Pixie it would be a decent Persona to use here. Another great strategy that is effective is using charm on the Immortal Gigas to negate his damage and turn him against his allies.
Cocytus Bosses
Boss 1 Brilliant Cyclops - no weaknesses (absorbs all magic)
Summons Soul Dancers (weak to ice)
This boss you will be fighting with additional mobs that heal him called Soul Dancers. You'll want to knock them down with Bufu skills, their weakness, to prevent them from healing the Brilliant Cyclops too much. The main boss here, Brilliant Cyclops has no weaknesses and he absorbs all Magic cast on him. Also he tends to cast Mabufula a lot which means you should probably avoid bringing Akihiko as that's his weakness.
Caina Bosses
Death Castle - The only spell that works on him is Zio
El Dorado Beast - They have Dodge Ice but are weak to Bufu
This is another fight with one big guy and two adds. Similarly the adds here are weak to ice as well. Strike them with Bufu skills to knock them down each turn that they are alive to minimize the damage they cause you. The Death Castle can't be harmed with any other magic than Zio. Take out the adds first then the big guy.
*Boss 2*
Harem Dancer x1 - No weaknesses, absorbs frost (Blocks Piercing attacks)
Merciless Maya x2 - Weak to Garu (Take these foes out first as they put up anti magic shields that can get annoying)
This fight should be pretty easy for you. I took in Mitsuru, Akihiko and Ken which has been my line up for every boss up until now. Just focus on the adds first and then take out the main guy.
Antenora Bosses
Judgement Sword - Attacks with Lightning (Zio) // Weak against Wind (Garu)
Brave Wheel - Attacks with Fire (Agi) // Weak against Ice (Bufu)
Ice Raven - Attacks with Ice (Bufu) // Weak against Fire (Agi)
These guys are the first real fight I had a bit of an issue with. I honestly don't recommend using the spell that these guys are weak against, they dodge the crap out of them. I actually try to find a neutral magic that they don't block or absorb that I can hit all of them with. Or at least two of them if you can't manage hitting all 3.
*Boss 2*
Shouting Tiara - Weak against Ice (Bufu)
Primitive Idol - Weak against Lightning (Zio)
Wrathful Book - Weak against Fire (Agi)
This boss fight is a lot similar to the previous one in the sense that you'll want to try and avoid focusing on each of their individual weaknesses. Instead you'll want to find a magic that works well on damaging them all that they don't block or absorb. That's the easiest path to victory in my opinion. Also don't forget to use items if you need to!