A little over a month ago, I created a table of magical power sources, which I intended to explain in more detail. A recent comment reminded me I still need to do that. This post goes into more detail on astrology as a magical power source. First, a reminder of what the power sources are. D&D magic has a two-step spell process: “memorizing” or preparing a spell before an adventure, and casting the spell during the adventure. The way I interpret this is that the prep part is what you’d recognize as a magic spell from non-D&D fantasy media: inscribing symbols on the ground, tossing ingredients into a brazier, reciting incantations, the usual ritual stuff. The magic-user raises magical power from some source during this ritual and links it to a short phrase and hand gestures which act as a mnemonic trigger during the actual spell casting. This trigger releases the power and causes the spell to take effect.
I’ve read several actual grimoires and occult books, from Francis Barrett’s The Magus through Crowley’s Magic in Theory and Practice, books by Eliphas Levi and others… too many, really. So my vision of what those rituals would look like is colored by that. Those books typically involve:
- Using astrology to determine celestial influences on the spell to be cast;
- Using tables of the names of celestial intelligences and spirits linked to the time of the casting;
- Divine names and magic words to invoke;
- Tables linking herbs, plants, animals, gems, metals, and other minerals to celestial influences.
On the simplest level, having astrology as a power source just means that spellbooks include an astronomical emphemeris and tables linking different magical effects to different planets, days of the week, and the like. For example, here is a chapter from The Magus about making talismans linked to each of the seven classical planets of astrology and what each planet governs. There are also individual chapters for each of the planets expanding on this, and later in the ceremonial magic section, the names of the 24 spirits that govern the hours of the day and night, and the angels, planets, and zodiac signs that govern each day of the week:
|Day Name||Angel Name||Planet||Star Sign|
The more limiting version of Astrology (listed in the third column of the magical power sources table) is Limited Time. This is the “when the stars are right” restriction. Instead of being able to prep any spell at any time, as long as the rituals are tailored for the time of the ritual, there are windows of opportunity that open up for prepping each spell type. If the magic-user is prepping a low-level spell, but misses their window, they have to wait a week for the next window. For higher-level spells, they have to wait a month, and for the highest level, a whole season or even a year.
The most extreme version of an astrological power source is the use of Planetary Rays. In addition to the time constraints, the magic-user must have special designed lenses or mirrors to focus the cosmic power emanating from the planet in question. The simple way to rule this is to require a rare substances (sands of Mars, essence of Mercury) to be added to the molten glass that is later ground into a lens shape. It mainly adds a monetary cost to replace a lens, possibly an adventure if a particular substance becomes temporarily scarce.
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