Dreamstuff is a substance of solified dream energy that the onirarchs of Dadauar use for most of their creations. Most of the tools and talismans created by the dreamlords are made of dreamstuff, and in many onirarchies so are the majority of the buildings in the cities. Hard currency in the onirarchies, those that use it at all, is also made of dreamstuff, rendering it very difficult to counterfeit. Even living creatures can be made of dreamstuff, as are the onirarchs' servants the batirines—or partly of dreamstuff, like the dreambuilt.
The onirarchs have developed many kinds of dreamstuff, but the four in most common use are fleshy, metallic, ceramic, and vitreous. Each of these has its own uses: fleshy dreamstuff is what the onirarchs typically make living creatures out of, while the buildings and implements can be of any of the other kinds (or other, rarer varieties) depending on their functionality and the dreamlords' preference. All kinds of dreamstuff, regardless of texture, inherently have a shiny, multicolored look, with all the colors of the spectrum mingling with white, black, brown, gold, and virtually every other color imaginable mingling in weird patterns that may be smooth and gradual in some places and angular and jagged in others. However, it is possible to change the color of dreamstuff with very little extra expenditure of energy, and so in practice most dreamstuff is less conspicuous, looking like ordinary flesh, metal, or clay or having some other simple color and sheen. It's also possible, and slightly easier, to tint the dreamstuff slightly but still leave its iridescence, which is what is often done with buildings. Thus the cities of Dadauar's developed nations might have buildings in varying hues of red, blue, and other colors, but all with an underlying play of different shades.
Dreamstuff is a versatile material, and can be made soft and pliable, brittle and friable, or very hard and durable, according to the creator's wishes. As a construct of magic, however, it does have certain vulnerabilities. Magically created, it can be relatively easily magically destroyed, such as by the spell "forceful dissolution". Rebels have developed a spell, "batirine disruption", specifically tailored to dissolve the living dreamstuff that makes up batirines. It's also possible to twist the shape of the dreamstuff rather than destroying it, through a spell such as dreamwarp. Similarly, it is possible through magical means to identify objects made of dreamstuff even when those objects are carefully designed to look like other materials; the "dreamstuff detection" spell was created for just this purpose. It is also possible, of course, to enchant objects with these magics, and some rebels carry around talismans designed to destroy or disrupt the onirarchs' dreamstuff creations.