Most of the time, the villain of a major story isn't just some big brutish warrior who smashes everything he sees. More often, the villain is a methodical planner who operates behind the scenes to put the big brutish warrior who smashes everything he sees right where the villain needs him to be.
As a gamemaster, you have to be able to portray a wide array of NPCs. What do you do when you want to portray a villain with a really high intelligence, perhaps one who is smarter than you? It's very difficult, sometimes, to portray characters who have abilities that differ greatly from our own. Intelligence is one of the hardest attributes to convey in a game. What exactly does an 18 intelligence mean? In the d20 system, 10 is considered the human average. There is always a chart in the core rules that tell you how much you can carry based on your strength, so you can easily figure out how strong your character is, but there's no handy chart that tells you how smart you are.
A high intelligence usually grants extra skill points, and in D&D, grants a wizard extra spells. However, there's no real guideline to tell us how a high intelligence should be represented. What we do know is that 18 is considered the peak of natural human ability for any attribute. So, does that mean a character with 18 intelligence is a genius? A super genius? The next Einstein or Tesla?
As a gamemaster, you'll need to figure out just how smart you want your villain to be. Luckily, playing a genius is easier than playing the same character as a player. Why? Because you can cheat! This is one of those times where bending the rules is perfectly acceptable, because it enables you to better play an intelligent character. Let's look at a couple of examples.
You prepare the spells for an exceptionally intelligent wizard villain you plan to confront your players at the end of a long adventure. When the fight begins, you realize the players have obtained abilities that make them immune to one of the wizard's spells, or they have developed tactics you didn't plan for, and his spells are no longer the best way to deal with this situation. What do you do? Well, an intelligent villain would have gathered information about his enemies. He would have found out everything he could about the party he was about to fight. In other words, change some of his spells in the middle of the game. You might not have planned for what the party was going to do, but there's no reason why your villain couldn't have predicted it. He would have planned for it, so changing his spells so that he can better deal with the party is a great way for him to anticipate and plan around them. I did this with a previous campaign, introducing the villain about a third of the way through the story, and having him show up to taunt the players occasionally as they continued their adventure. They never knew when he'd show up again, and I even told them that any spell or tactic they used in battle could potentially be seen by him and he'd be able to plan around it.
For our second example, suppose your players get the upper hand on your villain before you wanted them to, or maybe you did want them to, who knows? Instead of killing the villain, they decided to capture him. What do you do now? Perhaps the villain planned to be captured. As the GM, you can easily alter a few things and have the villain put an escape plan into motion. Perhaps the villain already has already paid off a guard, or already knows about the loose brick in the prison wall, or that the proper leverage can lift half-barrel hinge doors off their hinges.
Be careful when using tricks like this. Make sure that only appropriately intelligent opponents get to change their plans in the middle of the action. Villains that aren't in the upper ranges of intelligence should have to deal with whatever plans they make and whatever happens if those plans fail.
