Rune magic works how Talad decided to bind it. Magic works, in equal parts, how people believe it works and physical laws. Turning sugar into ash and ash into sugar would require expending that energy from somewhere (16190kJ per 1kg when burned, more energy for a conversion to pure carbon and back). The crystal powers magic, but only so much energy is collected and radiated by the crystal at any given time. Luckily, people are limited by how much energy they can channel at a time, so the sky doesn't go dark when a mage starts experimenting. The difference between ~natural magic and Talad's magic is that the latter does not require the caster to work with details. Things like power absorption, density and range, are preset to minimum density and maximum range; and always from the crystal. I assume when he bound it he used a single extra plane to facilitate magic, so it would interact easily, whether or not the users intended.
I guess any magic user would exist to some extent on more than one plane, but they wouldn't be able to store their intelligence there without a container. Or if they could, it would be a losing battle to keep their mind from matching their form or slide back into it.
