Jeffrey A. Bell has written:

'Industrialization and Imperialism, 1800-1914'

'Philosophy at the Edge of Chaos'

Beat all of the duelists in the Neo Space portion of the World of Chaos, five times to unlock the pack "Chaos of Nothing". It contains Uria. The duelists to beat are Neos Alius, Plasma, Malicious Edge. To unlock the World of Chaos, if you haven't already, clear the challenge at the final gate in World of Order.

Chaos is a Water-ish type of creature who came from the Master Emerald, also if you feed him a Chaos Emerald, he will turn more powerful: Chaos 0, Chaos 2, Chaos 4,Chaos 6 & Perfect Chaos.

CHAOS. CHAOS, i tell you. CHAOS!

When fighting the manikins, it really depends on you. When fighting Chaos, use a long-range type of character, such as Terra. The reason for this is that you will be fighting Chaos in the Edge of Madness which is a really small stage. Best to choose a character that can attack at any distance.

Heres a hint: Use a character that is at least at level 70. You have a better chance to win. I beat Chaos with Cloud because he was the only level 70 character I had. :P