Previous: Of Kobolds And Arcane Magicks, p4

Pictured: an uncontrolled spell discharge in progress. Worry not, the kobold survives.

[Excerpt from: G. Gerradale - On Cultivation of Sertevian Lettuce]

While the basics of spellcasting are beyond the scope of this work, it is prudent to nevertheless reiterate them before proceeding to explore the finer details. The caster first establishes a containment field around their focal point and maintains it throughout the casting sequence. Failure to do so will result in an uncontrolled discharge (some spell varieties have specific terms for such events, such as blowouts for explosive projectile spells). Once the field is established, the caster channels mana into the spell proper, creating a charge or producing a continuous effect; additional mana may be committed to the containment field during this stage if more power is necessary. Once again, the only thing shielding the caster from the spell's effects at this stage is the containment around it.

The properties of the containment field dictate the spell's T-class and shape. With respect to T-class, fully enclosed containment is used in projectile and burst spells, whereas partial containment corresponds to channelled spells. The classification of spell shapes is more complicated and will be broken down by T-class.

> Projectile spells <
Projectiles are able to maintain their own containment field once released by the caster; the amount of energy accumulated in the field determines the projectile's lifetime. The field's failure mode can also be manipulated with sufficient skill: the humble fireball, for instance, explodes in a purely spherical manner by default, but it has several (relatively common) variations with shaped explosions, such as linear (for single-target application) and planar (for multiple targets on level ground).

> Burst spells <
Burst spells are essentially projectile spells with zero lifetime, triggering directly in the caster's focal point. In this case, manipulation of the containment field's failure mode is essential, in order to direct the effects away from the caster. The variety of shapes is thus generally limited compared to projectile spells, though with enough ability even planar spells can be cast in this manner - as long as the caster is able to get their fingers out of the way before containment fails.

> Channelled spells <
Derived, in turn, from burst spells, channelled spells are only partially contained and start discharging their effect (in a controlled manner) as soon as the channelling of mana begins. Being close to burst spells in concept, channelled spells are generally shaped the same way, the majority being a continuous stream of adjustable width and speed. Despite this similarity, however, they require greater concentration to use, as the manually shaped containment field needs to be maintained concurrently with the effect channelling. This makes channelled spells less popular for combat, but the undeniable utilitarian value of low-power continuous effects makes them useful for more mundane tasks - which this work discourages for reasons of safety. The number of amateur casters suffering property or personal damage from a loose firestream, for one, is still much too great for how widespread chemical lighters have become.

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VIII.e - Dual Casting

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If you're reading this work, you've likely attempted to dual cast a spell of your choosing at some point. You've also likely suffered an uncontrolled discharge during said attempt moments after you felt unexpected feedback from the containment field. If so, you've encountered the reason why dual casting has the reputation it does - containment snapback. The following is a general explanation of the effect; for in-depth analysis, refer to Ch.IX.c.

Given two focal points in close proximity, the containment field has two metastable shapes:
1) one sphere centered between the focal points;
2) two conjoined spheres, each centered on one of the focal points.
This distinction presents a complication: a dual-focus containment field has the potential to snap out of its intended shape #1 and into a lower-strain configuration #2 (see Ch.IX.c for calculations). This transition can be triggered by a multitude of factors: failing to account for the increase in baseline containment requirements during a dual cast, accidental overseparation of focal points, etc. The margin of stability for shape #1 is fairly narrow in practical terms, compounded by the fact that feedback generated by deviating from equilibrium is difficult to filter - until the field begins transitioning to shape #2, which reduces its volume for a given level of containment energy and causes a sudden increase in charge density. The latter generates a jolt of overcharge feedback that is easily recognizable, but sudden and too brief to react to; what usually follows is an uncontrolled discharge of the spell.

To sum up, the strength of dual casting is also its drawback - while the caster is able to create a larger containment field and thus pack a greater charge without increasing the energy density, it comes at a cost of having to maintain a delicate balance between two distinct focal points in close proximity of each other.

As a side note, the widely circulated hypothesis that kobolds may also be capable of triple casting thanks to their oral focal point is not substantiated by any solid evidence. While the idea that such capability would be a closely-guarded secret is not without precedent (dual casting itself was intentionally shrouded in superstition for centuries, according to numerous historical sources), this work holds the opinion that such practice is simply infeasible due to the sheer complexity of balancing three focal points simultaneously.

[Editor's note: despite the name, this is a textbook on advanced spellcasting; G. Gerradale is known both for his research as well as his (at times obsessive) commitment to safety, part of which is naming his advanced works in a way that disguises their nature from laymen.]