Delta Radiation

Delta radiation (alts: δ radiation, δ-rays, delta energy) is the Ariad's primary source of magic.

Sources of delta radiation

Delta radiation is present in high concentrations throughout the Ariad; it is thought that the planet's mantle has a high concentration of delta-producing elements. Certain rare minerals produce high levels of delta radiation; sometimes their radioactive activity is so high as to be perceptible to humans. More common, however, are minerals which merely trap delta radiation, causing a charge to build up in the mineral over time.
A few species of animal are also known to be sources of delta radiation. These are extremely rare, and the mechanism by which they produce delta radiation is unknown. The most well known delta-radioactive species are phoenixes, which are apparently immortal. Keeldragons are also powerful sources of delta radiation.

Delta radiation in the natural environment

The level of delta radiation varies across the Ariad. The Ariadic Ocean, the planet's single body of water, has a delta radiation level between three and twenty times higher than terrestrial levels. The cause of this is thought to be due to differences in the elemental composition of the planet's oceanic and continental crust. Many regions of Quesela, the Ariad's largest continent, experience pronounced fluctuations in delta radiation. Bursts of high activity are common, although their cause is still unknown. Due to the dangers posed by these conditions, Quesela has never been colonised by non-native species. Although geological records are limited, it is thought that delta radiation levels were once substantially higher on the Ariad than they are today.
Many, if not all, forms of life take advantage of delta radiation on the Ariad. Many native species have evolved to channel delta radiation to accelerate enzymatic processes: if removed from an environment rich in delta radiation, they would be unable to survive.
One obvious example of delta radiation's effects is gigantism, with many of the Ariad's native species reaching sizes virtually impossible on other Earth-like planets. Extreme within-species variation is also common, perhaps due to highly mutated organisms being more able to survive in a delta-rich environment, or due to the accelerated rate of molecular evolution triggered by delta radiation.

Physiological effects of delta radiation

Magic

Technically, magic is defined as "the deliberate manipulation of the flow of delta radiation by a sentient organism". However, in colloquial language magic is often used to describe any delta-radiation catalysed process or ability, as well as delta radiation itself. For example, telepathy is not strictly a form of magic as it is a passive process, with many non-sentient species also exhibiting telepathy, while telekinesis is magic as it requires conscious, deliberate control. Both of these abilities are generally referred to as magic, despite the technical difference.
Delta radiation can be channelled from the surrounding environment to influence or trigger almost any natural process. Almost all humans, elves and halflings are able to channel delta radiation (colloquially "are able to use magic"), although extensive training is required to do so effectively. Generally the more complex the substrate or energy intensive the process, the more difficult the task is to perform. Simple physical reactions such as boiling or freezing water, creating sparks or levitating small objects can be achieved with practice; chemical reactions and manipulation of complex materials (especially organic matter) will usually require formal training unless an individual's magical ability is exceptionally strong. For example, healers may train for decades before being able to reliably manipulate human flesh. It is theoretically possible to trigger nuclear reactions using delta radiation, but such an ability remains unheard of.
A few forms of magic are unique to certain species. For example, elves are the only species able to directly manipulate delta radiation (this has lead to the myth that elves are capable of killing a person with a single glance by shocking their body with delta radiation - in reality, this ability is extremely uncommon if not unheard of). Halflings and dwarves tend to have a much greater affinity for telepathy than other species, although this ability is not unique to them.