Tricks for GMs
"A fluke of chance, I rolled 100! My supposedly incredible liar villain was just caught lying by the PCs! His plans are going to be ruined. Is my campaign as well?"
"Ah Fate, you laugh in the face of mortals! A PC rolled 01 and beat my champion with a wound! My villain was killed in the first round of a duel, is my campaign failed as well?"
See, if you've been in the above situation, you might have thought it was a problem. It wasn't, although I've thought the same as well. But it's one of the few situations when "relax" is actually an advice that solves your problems. You've got to be relaxed if you want to roll with the flow. And you kind of have to, in such a situation! (Which is why I love these situations, but that's another story).
The trick is to remember this. Whatever happens, it drives the game forward! Well, some things might end the campaign right there. There will be other games, though! And at least, you have the time to make a fitting resolution of the campaign. (Or to think of a bittersweet ending. Players with a flair for dramatic love them). What could possible make for less work than using other people's input to drive the game? You don't even have to read a module in advance. Unless you want to, of course.
So, back to our unexpected outcomes -- whether it was a player devising a totally unexpected plan, or a die rolling maximum value 10 times in row. So, whatever happened, it was something unexpected. This means something else was at work. Ask yourself the following questions. Well, not who did what -- presumably you know already, being the GM. And if you don't, these should be your first questions.
Why did it succeed against the odds?
Is the enemy in love with the PC? Is he feeling remorse, making him hesitate? Did an argument strike a chord in his soul? Yes, this looks like retconning, but remember, critical successes are when fate conspires to be on your side -- and who's to say he didn't see the error of his ways for a split second, feel regret at a step he took long ago when he should have been concentrating on the fight or argument? Still, I avoid this track. But a villain bleeding his last droplets of blood and smiling at the PC who stabbed him in the chest. Give him last words. (In my games, every major PC or NPC can get last words, unless killed by decapitation or strangulation, and that's an actual rule).
"If it had to happen, I'm glad it was you".
How would the PCs react to this classic storytelling device?
Imagine a mook who fought the PCs off for a round or two when all the others were down. If they didn't kill him off, did he become a Wild Card? If he was that determined, did he come back from the dead for a second chance? How would he try to separate them to get a duel this time? I've got a surprise for you next session guys!
Imagine the henchman that did the same. He didn't break. He didn't run. He fought an ogre to a standstill while they dealt with the other ogre, and survived, or is dying like a hero. Why did he fight for them? Did his brother have a bad gambling debt he was willing to risk his life to pay off? Even if that was the final fight, what are the PCs going to do about helping the loyal and able guy?
Imagine the villain waving a plot in the court. Did he blunder because he felt disgusted with his own treachery? Out of love for a PC? Did he decide and conceded the argument? Is the reason only they saw through his lies that they're too much like him? A troubling thought, but possible with some PCs. If it's true, did he realize this as well? What is he going to do about it? Remember, you might have just shifted the game to a story where they know who's responsible for a plot...but they have to avoid acting like him to stop the plot. Again, you just got a classical storytelling moment without pushing for it.
What consequences does it have?
Again, let's go through these same situations. Practice shows they're the ones that bother new GMs the most.
So, the villain is bleeding his last droplets of blood and smiling at the PC who stabbed him in the chest. Was it justified? Was it murder? Can his plans progress without him and would they be successful, but easier to divert, or doomed from this moment on? Who else is going to profit from his death?
Maybe his lieutenant wanted to get rid of him to marry his wife. Does she want it, however? Or maybe his second in command wanted to take his lands for himself. Did the villain have a son, and if so, would the guy try to dispose of the rightful inheritor? Who would seek revenge, to the point of starting a campaign against the PCs?
Imagine the mook that fought the PCs off for a round or two when all the others were down. Were they in a hurry? If they're late, what complications do you introduce? Did anyone hear the noise and call alert?
Imagine the henchman that fought bravely on their side. Did he get recognition? Did he save his brother from debtors? Is he going to ask for help, or more money to settle the debt? If they start trusting him, is he a man to be trusted, or a good fighter with questionable morals?
Imagine the villain waving a plot in the court. The PCs just caught him lying, but "sense motive" isn't really proof against the vizier. How do they prove their point? Where to look for clues and proof to expose him?
Did he notice they didn't believe him? Maybe you just shifted the campaign to a game of surviving until they can deliver this information.
Last question now, or at least, last you can ask in any situation.
How people would react to this amazing success, if they can notice it?
So, the villain is bleeding his last droplets of blood and smiling at the PC who stabbed him in the chest. Was he the best swordsman in the country? Would people want to hang them, sing their praises, or challenge them to a duel to prove they can beat whoever defeated that guy?
Imagine the mook that fought the PCs off for a round or two when all the others were down. Would people look down on them for ganging up on this guy? Would they lose respect for "taking so long against a simple soldier"? (I don't recommend this one, but it's possible, and you know your group best). Would he be remembered a hero? Would his fight inspire a youngster to develop an Iron Will Fist style made to emulate his dying prowess?
Imagine the henchman that fought bravely on their side. Same thing, and same problems, with who gets the praise. Most groups are very picky about it. If he gets the praise, even without wanting it, would they still help him? If they don't, would people still respect them?
Imagine the villain waving a plot in the court. Nobody else would know that they spotted a lie -- he wouldn't't be much of a liar if everybody spotted it! But now they've got to do something about it, right?
If he's got good standing, how do people react to accusations, or any action against him? Basically, maybe they save the country.
Will the country thank them, or brand them traitors and rebels? Is a country like this worth saving (yeah, I know, but some PCs are likely to ask)?
Of course, you might also ask other questions. But it's a good thing to have a ready list, if you're going to use it when you're surprised anyway!
Granted, some of the above questions are more appropriate for one situation or another, which is reflected in the answers as well. Some would just give an unexpected twist, other would generate whole new threads. But the good news is, you don't have to use only one of them! Use the dying villain's last words to hint at some ambiguity, hit them hard with the consequences and his good PR techniques!
Try it. You'll see the adventure basically writes itself!

