When I saw the Levers prompt I immediately thought to the levers a GM gets to play pull to modify the play style.
Make combat more dangerous, just by playing mosters to their full ability, and you will change the game.
Be mean with the magical loot and toys and the play style will swing toward the magic users much faster.
Pile on the loot and the game can get pretty gonzo pretty quickly.
One of the levers I like the most is the Fail forward/fail backward lever.
When you start failing forward, for example the player fluffs up a skill roll but the character succeeds, you just introduce an implication further down the line, every failure adds something to the story.
Take this example:
A character tries to chat up a town guard of the opposite sex. They make or rather fail a charisma check. Failing backward would probably mean that the character gets the brush off, that episode is over.
This time we fail forward. The character fails the charisma check but the guard still seems interested and gives the character a time and place that they will get off shift. What the character doesn’t know is that the guard is in fact the infamous Black Widow serial killer…
That version of the events turned a failure in to a side adventure.
How far you push this lever will change your games. For the player, if nothing bad appears to happen when you fail, they are much more likely to try stuff. No one is risk averse when there is no risk. This then leads to more adventurous play and greater risk taking. All of which gives the GM more opportunities to make the characters pay for their failures in ways that are fun to play through. This is, after all, a game that we play for fun.
So Failing Forward is my favourite game play lever.