Thaumaturgy (and dweomer, its statistically-identical discipline) is one of several new d20 magic systems introduced in Eclipse: The Codex Persona (pg. 100-106). More specifically, it’s one of the magic systems that’s based around skills, giving that particular d20 subsystem some much-needed teeth.
In thaumaturgy, a particular magical discipline is divided into eight sub-disciplines, each of which has its own associated skill. If a practitioner of that style of magic wants to create an effect, then he has a make a successful skill check with the relevant sub-discipline (and pay the associated cost), and on a success the spell is cast.
There’s actually a bit more to it than that, but that’s the basic outline of how the system works.
The best part of this style of magic (at least to me) is that coming up with the eight associated skills for each particular discipline is something the player does. That means that each player is likely to come up with a different set of particulars, so that even the same theme will have different particulars depending on who uses it. Between that and that the effects generated are free-form, this means that no two users of thaumaturgy will be alike.
To whit, below is a sample field of thaumaturgy, based around a particular type of enchantment.
Manipulating emotions is a particularly insidious way of controlling others. Rather than subverting someone’s will, enchantments change how they feel about things while leaving their responses intact. The results can often be profoundly confusing, if not disturbing, for the victim long after the actual effect has ended. Wielding such invasive magic can come with a high price, however; few people can bring themselves to fully trust someone who can tamper with the most intimate parts of them.
- Anger: Creating not only surges of adrenaline-fueled rage, this magic can also induce lasting hatreds and deep enmities. This can also curse an individual or location to become an object of scorn for certain groups, or even – at high levels – for everyone.
- Anticipation: The opposite of surprise, anticipation causes something to seem to be more noteworthy than it otherwise would be. Not only can this boost situational awareness, granting combat bonuses and tactical insights, but it can be used to grant insight into mysteries and dilemmas that have no obvious solutions.
- Apathy: Not just boredom, apathy can be the complete lack of an emotional response. It can negate most emotion-based magic, as well as shield from pain or alignment-based effects. At the higher levels, this can be used to induce catatonia or hibernation.
- Fear: Not just immediate panic, this type of magic can produce anything from low-grade anxiety to bouts of fear so strong as to be lethal. This magic is often placed on an area, causing it to be avoided by the locals.
- Joy: Bringing forth happiness can not only counter fear and despair, but also creates powerful bravery and morale-boosting effects. This particular field of magic can become highly addictive to those that are regularly subjected to it.
- Love: This creates any sort of positive fascination. It can range from basic charm effects to powerful obsessions. Ironically, actual love is very difficult to create, and tends to be short-term.
- Sadness: Feelings of loss can be used to sap a person’s will to fight, saddling them with morale penalties or even forfeiting actions as they lose the will to carry on. Severe sadness effects can cause a target to become suicidal.
- Surprise: Surprise deals with being unaware of something, resulting in penalties to reactions. This can also be used to make parts of the immediate area seem subconsciously “unimportant” to the point of being unnoticed, while stronger spells make it so that key connections and revelations are overlooked or ignored.
As with all free-form systems of magic, what’s above are merely suggestions. The ultimate arbitrators of what can be used with any particular system of magic are the player’s imagination and the GM’s administration.