"The Palace of Plenty" was one of the best Oriental Adventures I've ever read. It not only used a wide variety of sources for materials in the adventure, but it also used them expertly, crafting an incredible adventure.
My one complaint is the lack of material expounding on the Void Dragon. What is it? Is it a god? If so, what's the information for clerics? I know web enhancements for issues are few and far between, but I'd really like to see more about this mysterious entity.
The Void Dragon (along with all the other Dragons) is not a god, per se. The concept of spirits and revered ancestral spirits (kami) is a common one in Oriental mythos, but calling it a god is stretching it. It is, however, an incredibly powerful being that quite likely has god-like abilities. I'll be giving a brief excerpt from the Rokugan campaign setting d20 book, to help out:
"...To see into a Dragon's eye is to see the depth of the cosmos; to hear its words, to hear the limitless wisdom of the Heavens. They are more than simply the embodiment of primal forces - they are the universe itself. - Akodo KanedaThere are seven Dragons in the Celestial Heavens, all of which represent part of the universe's foundation. The five Elemental Dragons (Air, Earth, Fire, Water and Void) are the best-known, and they are joined by the Celestial Dragon and the Thunder Dragon to hold the world together. They represent that which is both pure and holy of their element, and are said to be more powerful than the Fortunes themselves.
The Elemental Dragons are tied more closely to Rokugan than are the other two. They were created with the universe, as the primal stuff of creation slowly formed into the five basic elements. These Dragons moved among mortals when the Celestial Heavens were much closer to the earth, and took great interest in them.
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Only the Thunder and Celestial Dragons directly interfere in the affairs of mortals very often. 'Often' to a Dragon is once or twice every hundred years; the Dragons sometimes appear to worthy mortals who ask for their guidance, or charge them with a duty from the Celestial Heavens. The Elemental Dragons choose to affect the moral realm through their Oracles and by sending mortals dreams or visions.The Dragons themselves are the lords of the Celestial Heavens, just below Sun (Amaterasu) and Moon (Onnotangu). They hold reality together with their very existence...They usually act and think independently, though they view one another as family. Each Dragon is the embodiment of an Element, though they can appear in any forms they choose."
The Oracles mentioned are mortal representatives that are charged with the Dragon's power. They are able to answer a single question asked of them, as well as several other abilities (I believe they were covered in the Magic of Rokugan book - it's an applied template).
I would hesitate to call them gods, as the religious systems between "East" and "West" are different. The shugenja and wu-jen represented in the Oriental Adventures (3E) book utilize the idea of kami as opposed to a cleric-priest point of view. I would view them the same way I view Lord Ao in the Forgotten Realms - they are incredibly powerful, but not worshipped in the same way. Offerings of incense and foods would be applicable (as this was considered a way to please the kami), but I think you would be more likely to hear from their Oracles that you would from the Dragons themselves.
Mind you, I have not read this adventure, so I'm merely speculating. When I have used the Dragons in my game (which I focused a campaign around), the players were sent on a quest to awaken the Dragons, who had fallen into a torpor, which caused regular natural catastrophes, as well as weakened shugenjas and no Oracles. The Dragons had absolute control over their elements: Air was able to fly perfectly and was incredibly quick. Earth was able to shape stone and wood, was very strong, etc.
Void I viewed more as a Jedi Master, if you will. Yoda in the extreme. Telekinesis, prophecy (more so than the other Dragons), mental communication and domination, mental attacks and so on were all part of its repertoire.
Part of the Dragons' appeal is their mysteriousness - I would say if you plan to use them yourself, be aware of their dominion (Fire, Earth, Air, Water, Void, Celestial, and Thunder) and just roll with it. They have access to the universe, and the universe is rather hard to quantify.