A candle, a bear, rug, chest...bear.
"There's a bear?"
"Anomalies are where the action is, creatively speaking."
A number of books I've read have said that average success is boring. Most of us expect to be able to walk across the room. The first time your child does it, it's a chance to jump up and shriek and enjoy the milestone. When you trip on your own pant leg, roll over, and spend fifteen minutes with the giggles before you make it to the doorway, it's either tragedy or comedy.
There are a lot of examples of things made just slightly more interesting because they don't go the way you expect. Pornography and comedy (and I fear there is a difference) is full of examples. ("Whoo-hoo, look at who I'm boffin'!" "Normally it'd be wrong, but it feels...sooooo....good.") To some extent, that's the theory behind random elements in gaming. "I didn't expect to roll a critical success/failure."
However, it's also the key to plot design. Conflict creates plot, but if "the good guy" is always successful, the story continues with less concern. It is the struggles of the hero, the occasional injury, the near-death match with the antagonist... that's what gets me involved. I can see I have another 270 pages to go, and while I as an author might spend 100 wrapping up the loose ends should the protagonist bite it, I as a reader have fairly certain meta-knowledge that this isn't the fight where it happens.
One has to be perceptive for the anomalies. The example that makes the title for this post is an old gaming clich? (which, as you notice, has the word "lich" in it, meaning "evil undead"), wherein the GM describes the room thusly:
"There's a candle, a bed, a bear, rug, table, some chairs, and nicely fluffed up pillows." Whereupon as a reader you see that I've put a comma between "bear" and "rug," the listener has to be sure that that isn't "a bear rug" so when the bear attacks (it's Goldilocks' house, after all) they're ready.
I read it to Rainbow K and asked, "What's in the room that's going to attack you?"She sized me up quickly. "Maybe the bed...the table..the chairs... quite possibly a pillow." She added "Candle and bear," after a moment. Her eyes clearly said, "With you as a GM, anything is possible."
She's going to be a great gamer some day.
Impulse. I know some gamers who are intense planners, seeing every confrontation like a chess game. I'll do what "doesn't make sense to be done next," as long as it still fits the game "mood." I will, in a game, make mistakes.
The Feng Shui RPG described one of my favourite "mistakes": to be the hero that gets kidnap'ed... after all, that way one can find out what's really happening straight from "the bad guys" themselves.
As a GM, I never force it. It's the anomalies waking up and crawling out, careful of the early bird. It's a call to listen for the "something different." Seek out the magic. Be an anomaly.