Is Proto-Babil possible?

[nick]

I mean, with 2 limit breaks yes, yes he is but with only one, it would be very hard because, he starts to heal and Light of Babil to the entire party below 200k hp.
At that point it would seem hard to live when you keep getting bombarded.

[Clever Cloaks]

Very much so. He's rather easy to beat once you understand his pattern. Here's the strategy I used playing on Android:
It's recommended you have stats maxed out (personally, I just maxed out Cecil's, or whoever you're giving Limit Break to, which should be either Cecil or Kain). At least be around Level 80, or so. Note that it's recommended to face him on a third playthrough to gather proper augments. Onion equipment, Adamant Armors and Ribbons are definitely recommended. Mostly, get the equipment witht he best Magic Defense.
My Augment set-up:
Rosa: Dualcast, Fast Talker, Omnicasting, MP+50%, Defend (Auto-Battle)
Cecil: Attack, Focus, Adrenaline, Limit Break, Darkness (Auto-Battle)
Rydia: Brace, Last Stand, HP+50% (I couldn't be bothered to max her out), Draw Attacks, Brace (Auto Battle)
Edge: Cry, Salve, Hide, Phoenix, Hastemarch (requires Bardsong, Auto-Battle)
I didn't use Kain or Fusoya for this battle. I say, if you have one of them, give them the same augments as Edge if possible.
Cecil, to make use of Adrenaline, has to start off with 25% HP.

-Start off the battle by casting Slow on Proto, and, depending on whether Rydia was killed before she could Brace, either revive her, or Haste the party. Have Rydia use Brace. Use Cry on Proto, and with Rosa's next turn, cast Shell on the Party. Cast Protect once all all of the above has been done. If Rydia is braced and has over 4000 HP, she'll survive Light of Babil. Heal her regularly.
-Meanwhile your Limit Break user (Cecil/Kain) should Focus three times. Once has reached that point, have Edge Hide, and, timing it right so that Rydia doesn't get hit by LoB and before Edge's ATB bar fills again, activateAuto-Battle to Darkness. Sometimes Hide will glitch and cause its user to come back to the field without you asking him to. Simply use it again.
-Attack(or Jump if you're using Kain. More Damage) Proto-Babil. The Damage should be between 80,000 to 99,999. Proto might counter with Laser Barrage, which is why Egde hides. If Cecil/Kain is hit, he'll probably be dead, so revive him and heal him only up to 1/4-HP. It's important to keep track of how much damage you've dealt Proto.
-Repeat the two above bullet points once. Depending on the damage you've dealt Proto by this point, you might have to heal him. He is scripted to use Divine Judgement and a powerful Heal Spell if he drops below 120,000/400,000. So, if you dealt 99,999 both times, you gotta cast Curaja twice on him this turn to keep his early scripted pattern.
-Repeat the offense.
-This turn, have Cecil/Kain focus three times again, but, don't have Edge use Hide. Use Auto-Battle to have Cecil buff with Darkness, and Edge activate Hastemarch. Once Hastemarch is active, have Rosa cast Berserk on your tank. If you're lucky and time it right, Proto won't have time to use Diving Judgment before you kill him, which should take two to three hits.

-There's a VERY slim chance that Proto might counter all of your tank's hits with Object 199. Very slim, but if it hits Cecil/Kain after it offs Rydia, it pretty much ♥♥♥♥♥ everything up.
-If the party, sans Edge, dies, you can bounce back. Bring him back to the field and Salve Phoenix Downs. If Edge dies, he'll use the Phoenix augment to revive all other party members, at the expense of all his MP. Once you've buffed again, revive him, and use an Ether on him so he can use Phoenix again in case of another emergency.
-You COULD reverse the roles of Rydia with Edge or Fusoya, but their defense Stats aren't that great, so Rydia is probably your best bet to take all the hits.

Hope it helped.

[nick]

Thanks a lot, mate.
I'll be sure to try this out.

[stoopk1d]

Yeah I did it on my 2nd playthrough with no Adamant or Onion equipment. Just had relevant stats maxed and Limit Break/Darkness/Focus on Kain.

Rough strategy:
1. Only attack with Kain while the boss is above 120k HP to avoid counters.
2. Limit break/darkness/focus on Kain
3. Countdown the boss's HP on every attack so that you know when he's gonna start healing
4. Once Kain does his final attack by himself to get the boss under 120k, unleash attacks from your entire party and you should be able to kill him before he takes you out.