This is a problem with the fantasy genre: magic conjures a plot hole. Usually an entire Swiss cheese of plot holes.
As soon as an author inserts a magical ability or effect, the maze of possible effects and consequences magnifies far beyond whatever that single thing physically does. Sooner or later, a reader will ask: if magic can do this, then why can’t it do that? Why doesn’t the protagonist foil the villain with X, or the villain counter with Y?
With great power…
Even the most benign magic has a dangerous dark side. If you can heal, then you can inflict harm. The ability to fly, teleport, read minds, or control fire quickly breeds temptation. It’s human nature. Go ahead, be selfish, be greedy, be vengeful. Use it to gain wealth, power, status. Seduce a lover. Seduce the people. Destroy a kingdom, build an empire.
For every magical saint there is a magical sinner; thief, assassin, tyrant. How quickly will the magically-endowed individual abuse any magical power? Turn it to self advantage? For every Kal-El, you’ll get a Homelander.
If magic isn’t a constant temptation, fatal flaw and tragic burden, you’re doing it wrong.
When the reader uses your magic better than you
Even the tiniest use of magic breaks the rules of our real-world experience. And once you show the possibilities of said magic, readers’ imaginations think up all kinds of scenarios where it could be used. Then they’re disappointed when it’s not.
Readers will invent all manner of unexpected use cases the writer didn’t conceive.
“So why doesn’t Rand/Nyneve/Merlin/Gandalf do X?”
The more powerful and multi-talented the magician, the more opportunities they have to short-cut the plot, foil the villains’ plans and solve the plot problem. But they don’t. This makes the character look stupid, the magic system inconsistent, limited, incomplete.
Play any fantasy role-playing game and you quickly discover that human ingenuity knows no bounds. The players will run with any magical ability until it breaks the in-game world, or else the game-maker stamps down with punishments, penalties, or changes to the rules. Even a ‘simple’ ability to grow or shrink objects is open to mischief. Grow a henchman’s appendix until he explodes. Shrink a dragon to the size of an ant.
The more characters possess such talents, the potential for chaos grows exponentially. But in most stories, it doesn’t. The author has to contain the plot, ration the magic, limit it and break it sufficiently to stay on course.
No fate but what we make
Nothing breaks a plot like the magic of time travel and precognition.
One of my protagonists can see the future. This implies a deterministic universe. She sees it, then it comes true. The future is fixed. If she can change it, then how can the vision be true?
It’s like all those time travel stories; the ‘change the past to save the future’ scenario. Do that without removing yourself from the timeline, or accidentally creating something worse (The Butterfly Effect). It breaks the logic of cause and effect. And it makes my head hurt.
Jovanka’s story arc reveals many possible futures like a maze; she has the power to choose a different path. It feels like a cheat, but it works for my story so take it or leave it, bub.
Magical Short Cuts and Spoilers
Why should the protagonist battle on the hard way if magic provides a short cut? March to Mordor? No, let’s teleport. Boromir’s dying? Let’s heal him? Can we trust Saruman? Let’s read his mind and find out.
Nothing punctures a plot like magic followed through. Which is why authors invent all kinds of ‘rules’ and limitations. More often, the author just shoves all that unbounded chaos into a drawer to maintain their tidy plot line.
The psychic priests of Eskalon
I have many issues with the magic system in my upcoming YA adventure. It includes a malevolent order of psychic priests.
The ability to read minds comes with all kinds of unintended consequences. Got a secret? They’ll read it. Got free-will? They’ll compel you.
Why didn’t the priesthood simply command the old emperor? Why don’t the mind-bending priests simply instruct the new council from the back of the council chamber? Expose any non-believers by psychic interrogation?
Right away I have plot holes.
Practical magic
How does anyone resist the commands the priest place inside their head?
I have three characters with immunity from psychic commands, two with their own magical talents and a third with a ridiculous degree of innate stubbornness. No one knows this until the Big Showdown.
Question: how many mind-bending priests does it take to command an empire? Not many if they control key personnel. We can rationalize that.
More questions: how long do psychic commands last? What’s the effective range of compulsion? How strong is compulsion? Does it overcome self-preservation, friendship, family ties?
As soon as you introduce magic, you raise questions. Questions create plot holes, because magic defies coherent answers.
The solution? Like any good tour guide, divert, distract, keep the crowd moving, show them the next exhibit. Don’t fall through the plot holes.