Something which I've been vaguely thinking about for a while is how spells in many games tend to be surprisingly assembly-line. That is to say, any given spell is often used universally, with variation between magic-using groups defined by their selection of spells rather than the spells themselves.
This struck me as a little regrettable. The guild systems that you'd expect to find in mediaevalesque worlds could inspire a rich array of secret magical techniques, and thus a great deal of variation. Similarly, there's historically a lot of competition between different major players in a field, between companies trying to make their own approach the most popular, or between national factions. In many cases either different groups prefer different trade-offs, or the details of a specific technique are kept too secret.
The example that first came to me was the simple knock spell beloved of Dungeons and Dragons. You cast it, and it magically opens doors. But it struck me that a set of magical guilds might well each have very different approaches to such matters, and indeed in a fantasy novel I'd hope to see that quite explicitly.
Here I attempt to explore this in my usual haphazard way.
For the purposes of this exercise, I'm postulating three magical guilds.
The Worshipful Order of the Moon are a theo-thaumaturgial order which practice magic as part of their religious traditions, or practice religion as part of their magical traditions - it's hard to tell. Their magical philosophy revolves around attaining a state of confidence, and expressing their will upon the world. As such, most of their spells essentially command reality to be other than it is. Their keywords are authority, deception, command.
The Amethyst Guild are a fraternal order of scholarly mages who seek to explore the nature of reality and open the doors of the mind, allowing them to ultimately transcend this world. Their philosophy is one of contemplation, experimentation and the exchange - with the confines of the Guild, of course! - of hard-won insights. Their spells rely on understanding the underlying nature of reality, using that understanding to manipulate it, or altering the way others perceive that reality. Their keywords are time, illusion, creation, subjective reality.
The Seekers of the Way are an esoteric group of mystics who seek to unlock ancient and new secrets and so gain mastery over the cosmos, thus ushering in a new age of wisdom and harmony. Well, in theory. Their philosophy is one of riddles, koans, and yet of reducing the greatest complexities to their simplest essences so they can be commanded at will. Their spells are all words or sigils which express power directly, moulding matter or unleashing powerful energies in their rawest form. Their keywords are power, strength, raw matter.
Several factions have spells to deal with locks, but the manner of these spells reflects the precepts and arts of the guild in question.
The Worshipful Order of the Moon: the Knock of the Mistress causes the door to open itself (authority, deception, command)
The Amethyst Guild: the Remembrance of the Key creates a temporary shadowy key that can be used to unlock this particular door, based on temporal echoes of its structure (time, illusion, creation, subjective reality)
The Seekers of the Way: the Sign of Opening selectively inflicts damage to the barrier, ripping doorframes from their place and shattering locks (power, strength, raw matter).
Perhaps a creature must be rendered immobile?
The Worshipful Order of the Moon: the Quiescent Decree instructs a mortal to be still; and they obey (authority, deception, command). The Investment of the Crown overwhelms them with awe so they bow to your demands.
The Amethyst Guild: the Endless Moment alters the mortal's perception of time, so that they remain still (time, illusion, creation, subjective reality)
The Seekers of the Way: the Sign of Binding wraps the mortal in invisible coils, holding them fast regardless of their strength (power, strength, raw matter).
What about this sheer cliff, whose face does not particularly lend itself to climbing down? Besides, that would be undignified.
The Worshipful Order of the Moon: the Subjugation of the Winds insists that the air is strong enough to bear your weight; it dares not question you.
The Amethyst Guild: the Turning of the Page illustrates that distance is merely a perception, and the top and bottom of the cliff are separated only by the thickness of a sheet of vellum. In the moment when this truth is demonstrated, they step from the former to the latter.
The Seekers of the Way: the Sign of Ascension holds the wizard aloft and gradually lowers them to the ground. Alternatively, the Sign of the Path reconfigures the rock of the cliff into a series of convenient stairs.
Regrettably, it is necessary to overcome a group of impudent bandits.
The Worshipful Order of the Moon: the Treacherous Word causes the bandits to turn upon one another. The Exchange of Masks convinces the bandits that you are one of them.
The Amethyst Guild: the Dawning of the Dusk accelerates time for the unfortunate bandits, wracking their bodies with exhaustion and decay. The Tail of the Peacock allows the bandits to see not only where your entourage are, but where you could be, confounding them while you pick them off. The Dream of Glory reveals to the bandits another world in which they are slaughtering you with glee, while in this one they stand twitching and gurning. The Mote of the Mountain allows you to grow to enormous size and crush the ruffians. And of course, there are many spells which conjure shadowy beasts or weapons.
The Seekers of the Way: the Sign of the Ram unleashes a wave of force upon the bandits, hurling them away with cracked bones and bruised bodies. The Sign of the Colossus grants you superhuman strength and size, allowing you to crush the bandits with physical might. The Sign of Wrathful Earth transforms the ground into jagged spines of rock that impale the bandits.