Which is to say that the GM says, “Okay, you’re climbing that ledge into the Baron’s lair, and it’s going too easily. I’ll throw in a GM Intrusion; you grab a loose rock, which tumbles out of your hands, hits your head, and you begin to fall.” The player can choose to refuse the GM intrusion, in which case he has to pay 1 XP for a smooth climb, or he gains 2 XP as a reward for story complication – and has to give one of those XP away to a player immediately.
XP, in turn, are a more dynamic resource than most games. You can save XP to level up, but you can also burn a point of XP to reroll a die, have another player reroll their die, make a task easier, and so forth. Monte estimates about half a player’s XP will be spent making the game easier, which in turn gives the players a little more control than the usual frustrating “I’ve rolled four critical misses in a row!” dependence on dice.