A Soul Phantasm, also informally known as a power or superpower, is the innate, latent ability to change an aspect or aspects of the Fabric.
Soul Phantasms are abnormal, preternatural abilities that allow the user to affect the external world in a very direct way, metaphysically speaking, without requiring an external mechanism or energy source to act as a medium (i.e. Magic). They are exclusively spiritual in nature; that is, they are abilities that stem from the soul, and are vastly determined by the nature of one's Domain.
In contrast to Magic, Soul Phantasms merely require the user's Mind Component to interface directly with the Fabric, but without the complexity of an Aetheric Interface or the inherent requirement of aetheric energy. In that sense, the mechanism by which a Soul Phantasm affects the world can be thought of a shortcut that directly links the Mind Component to the Fabric in order to perform alterations directly. Magic by this definition would have the Mind Component be mediated by the Aetheric Interface, and superseded with a Magical Function that then rewrites the Fabric, but Soul Phantasms entirely skip these intermediary steps.
However, there are several natural limitations that prevent Soul Phantasms from having an effectively unbounded potential. Without exception, all Soul Phantasms affect an individual quality of reality, which is largely determined by the user's Domain. This means that Soul Phantasms very commonly manifest as abilities with thematically-restricted domains of power, with Elemental forces or basic aspects of physical reality being the most common, and thus fairly ubiquitous. This is known as the Range of the Soul Phantasm. Examples of such Soul Phantasms are "manipulation of fire", "manipulation of earth", and "manipulation of light", between others.
The second limitation is in respect to "talent", or simply the limit of the influence a particular person can exert with their Soul Phantasm. The "power level" of a Soul Phantasm is dictated by the user's capacity to exert dominion or control of its corresponding sphere of influence, and while this is technically not a finite resource, there is an upper limit in a person's ability to change the Fabric with their Soul Phantasm at any given time. This limit is variable in nature, with factors such as base skill, skill ceiling, and rate of growth (the sum of which can be defined as "talent") contributing to an individual person's capabilities, but an upper bound of influence will always exist.
The exact mechanism through which a Soul Phantasm exerts control over an aspect of the fabric of reality is unknown. The soul is indisputably the source of Soul Phantasms; more precisely, they are the result of the interaction between metaphysical openings in the Radix known as Wells, the soul's Domain, and the Radix itself. The Wells filter a discrete form of energy (which several schools of thought denominate as Od) from an unknown source (thought to be the Fabric's Origin), which is channeled through the soul and reconfigured based on the soul's Domain and its resulting Soul Phantasm, before finally being shaped by the Mind Component in order to directly alter the world. In that sense, this potential output from the Wells directly translates to one's ability to exert dominion on the Fabric; with the upper limit of influence being directly correlated to the intensity (or "quantity") of Od the Wells are outputting.
The standard nomenclature of a Soul Phantasm is to append the corresponding root of the concept with the suffix "-impery", which implies the nature of dominion and control over the concept (e.g. "manipulation of fire" being pyroimpery, "manipulation of earth" being geoimpery, "manipulation of light" being photoimpery). However, this nomenclature only broadly categorizes the Range of the Soul Phantasm, and thus does not fully describe Soul Phantasms with more thematically-specific Ranges. In such cases, a pseudo-binominal system is often used to categorize these Soul Phantasms: by first broadly denominating the Range (more often than not, with "-impery" nomenclature), and then specifically denominating the Soul Phantasm itself (by using a proper name).