The dark aeons quest is the longest, most dificult quest of the game. They all are high powered bosses with lots of HP, beginning at 800K for Dark Valefor, and ending in 8M+ for Dark Anima, and averaging 200+ stats for each of them, except the final Dark Aeons, who have 255 stats in every characteristic.
After defeating the Dark Aeons you unlock the hardest fight in the game, Penance. A tough M********* Piece of S*** who has 10M on his body and two arms that have 500K each, and they hit you for 30K damage each, except the ultimate attack of Penance, which deals about 70K. On top of that, they all have 255 stats, meaning they pretty much maim your team. I have managed to defeat them without using the Zanmato strategy, which what almost everyone uses, but it took me 3 tries, and two hours of fighting.
PS2 games are region locked, but you can mod your ps2 to play them.
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