Lightnin'! Welcome, welcome...aaaahhhhhhhh... Yes, the final BasedGod, he will be comin' shortly. Sorry about the long wait, BigB has been sleepin' for quite a while.
*I know this is 2 years late* He has 4 forms in his normal mode, which is on your first playthrough. A rush phase, a magical phase, a physical phase, and a stagger phase. In rush phase, he casts doom, which goes away once you beat his first form. Magical and physical phases are mostly self-explanatory, except magical BigB has Monad Beget/Wings of Destruction, which deals massive damage and even more if you don't take the adds. He also uses Genathylic Hymn, which causes Dancing Mad if he isn't staggered in time. If you do, it becomes a Falling Star. In his physical phase, he casts Almagest (a blast ray like a Gaster Blaster from Undertale) and Supernova, an unblockable attack which deals about 6,000 damage, and you can't change Schema once it is cast (he idles a long time before casting.) In his last phase, he must be staggered, or else he wont take much damage (1%). He also casts Heartless Angel, which, unless perfectly guarded, brings Lightning to 1 HP. He also casts Damnatio Memoriae, which kinda staggers/launches Lightning if not blocked during any portion of the attack. Once he is staggered, he takes 500% damage and can't do anything. In New Game+, if you complete the Ultimate Lair by defeating Ereshkigal, you unlock Bhunivelze+, who has a different pattern: He skips his rush phase, and combines phase 2 and 3. He starts with phase 2, and switches to phase 3 after Falling Star/Dancing Mad. In phase 3, he has access to Hypernova, which does about 45,000 damage. Prepare some Phoenix Downs/Wings. He then switches back to phase 2, and the cycle continues until you whittle down his HP bar (14,000,000 in Hard Mode). He then goes to phase 4, and casts Doom on you, which goes away after the stagger, but he recasts it if you don't defeat him before he gets up again, or you are revived by any means. He also has access to Cataclysm, which is essentially Quake, and Elementaga, which is scary AF. His strategy remains the same, however. I hope this helps at all.
Note: this is going to be a bit longer than I expected... I 'm not sure how to explain it, but I'll try to go a little bit more in-depth. First, it's easier to beat Bhunivelze+ if you've done all possible sidequests each playthrough (for the stat increase). You'll want to save before the final day so you can get the items I have at 6:12. Have your three schemata set up like I do with their upgraded equipment and weapons and accessories. You don't need the Guardian Corp schemata; Equilibrium+ is better since it increases ATB recovery of standby schemata, but the other two (especially Martial Monk) are very important. You can make Sacred Knight (Ultimate Warrior) into a Magic-Immunity garb by giving it the Preta Hood and the Runic Ring; any magic attack will do zero damage even without guarding, so you can keep casting spells without getting hurt, increasing the stagger gauge (but your attacks will do very little damage. I upgraded the shield Ultimate Warrior uses, which, along with Heavy Guard*+, means any guardable attack will do zero damage when guarded against (some One-Hit KO moves require perfect guarding for this to wok, but those moves are possessed by only two bosses). Anyways, cast Deprotect and Imperil at the start, and if Bhunivelze starts the fight by going into wind form, then you're in good shape for the setup I have. Just keep tossing out lighting bolts until he staggers, then use an Enthunder potion and a Nektar of the Gods[Omega] potion, switch to Martial Monk and keep hitting him with Whirlwind Kick. As long as Deprotect and Imperil are still on him and he's still in Wind form, hitting him with a full Whirlwind Kick combo will prevent him from attacking. Be careful when switching Schemata to let Martial Monk's ATB gauge recover a bit. Make sure to cast Deprotect and Imperil when the icons start blinking; Imperil is especially important since Bhunivelze's attacks won't be interrupted even if Lightning is attacking with the element he's weak to. When he switches to another mode, (example: fire form), drink the potion of the element he's weak to. (fire form is weak to enfrost -> ice form is weak to enfire -> thunder form is weak to enaero -> wind form is weak to enthunder). You make want to drink another Nektar [Omega] potion to keep the stat increase. You may want to use Overtime so you can refill Martial Monk's gauge without having to switch schemata and quickly do a tin of damage to Bhunny. When his health is reduced to 0, he's basically the same as he is in his third(?) form in Normal Mode. Just keep hitting him with Lightning bolts and Heavy Guarding his attacks. If you want to get physical, you'll want to use attacks with high staggering power. Don't worry about the Heartless Angels, they can only reduce Lightning's health to 1, which shouldn't be a problem since Bhunny's attacks are easily guarded. Keep casting spells to stagger him, and once that happen, it's basically game over for Bhunivelze. I hope this helps a little bit. This is my third playthrough (second on hard) so you may lack my stats, but the important things are what I put on my schemata. Martial Monk is the key here and it's the Number 1 damage dealer. Try to practice the Perfect Timing Attack for the Whirlwind Kick, which increases the amount of damage it does by a good bit. You may find a better tips on a forum, but just keep trying against him (there's no penalty for losing).
ExodineThe2nd Thanks great tips! I'm on my 3rd playthrough, 2 on Normal this on Hard, I'm pretty close to your stats except Strenght at 5000 and some costly mid-high tier shields/maxxed out weapons. I will try it I hope to defeat him.
can you help me? I'm finishing the second time in hard mode and I have PUNCH LV 2 from Martial monk, but I do not have the Accessory Warrios badge. I'll be able to apply the same damage from attacks on the last boss ??
how can you enjoy fight scenes when you can't see what's happening? this is all so blurry I hate the battle modes employed since they did away with turn-based pretty much since 10/12
this a year later but, as much as i like replaying old rpgs with turnbased. omg i find it soooo slow and kinda boring. these include the old final fantasies.