[quote name='TahoeMax']When you start buying Forgotten Grimoires at the bazaar you start getting plenty of drops. If you're willing to sit back and build up a chain, you can REALLY watch the loot flow in. I've gotten 8 pieces of loot from a single monster. I rarely steal from regular enemies, but it's sometimes worth stealing from bosses, since they tend to have some more interesting stuff.
I just finished piecing together the medallions, so i'm off to get Chaos now. I really can't stand the fact that the medallions are next to impossible to get without cheating and looking at a guide. That, the Zodiac Spear conditions, and a few other things that you pretty much can't get without a guide are my one real gripe about the game.[/quote]
I just beat him, and he is a

ing prick.
The two bosses before him are easy, but you'll probably want to run out and save before Chaos. I barely beat him.
For Fury, have two healers and a tank with Decoy, berserk him if you wish. When Fury gets low on life he starts popping Baccus Wines and berzerking himself. If you have one of your healers set to constantly cast dispel, he spends all his time using items and rarely hits you.
The behemoth is easy. Just have two fighters and one with decoy and beat the piss outta him. He has an attack that causes about 4k damage and Immobilize and disable, so have esuna on both fighters and heal with your healler. Bring a couple of Chronos Tears as one of them uses stop a lot.
As for Chaos... The reason he's so hard is because you can't use Attack. You're stuck with magics and technicks. The guide recommends Soul Eater and Bio, but save all your mana for healing. The chaos jets only have about 5k HP and go down pretty quick, but Chaos sucks. Have your main tank running with bubble and protect and then give EVERYONE haste and shell and give your healers faith.
His normal attack isn't too bad, ~1000. He has a magic attack called Wirlwind which will hit for about 4k WITH shell. The thing that makes him so bad is Aeroja. It hits everyone no matter where they are for about 4k with shell and sometimes confuses you. Have your tank run away from him while your healers buff everyone up and pray you can survive.