Xaelvaen
Stuck in the 90s
I was just wondering how you handle it when the module says that a villain escapes when he is about to lose the battle, but actually has no means to escape combat-mechanics-wise (grappled, etc.). Would you just force it and just override any combat rules and switch to narration mode or just let the villain die if he can't get away through combat means, making the players miss out on potentially fun pursue scenes?
Well, I never 'break the rules' to ensure the escape, but I do have a wide list of contingencies available. The big rule here is, keep it new and keep it organic. If the same method is used every time you have a villain escape, it does break your verisimilitude (especially if it's multiple times in a single campaign), but players can build up this distaste for it even if it's over multiple campaigns. Also keep in mind, there are -many- ways for a villain to escape and the players not even know it.
As others have mentioned, giving them a magic item to perform an escape (misty step, dimension door, etc) is a simple way.
Sometimes, however, it's best to let the party go ahead and kill the villain, because escaping from a weak mortal coil is a far better escape for some. The villain can return as a spiritual being (wraiths are always fun), or even a physical undead using whatever lore you desire. His body could be discovered by a Necromancer and be naturally reanimated (those are always a great plot twist - the players encounter the person they could have sworn was dead, can't visually tell if he's undead or not - wonderful player expression on that one).
Just keep the means of escape fresh with each particular encounter need, and make sure its logical to the villain. If I'm grappling a badguy cause he looks flighty, and he manages to disappear with a crunch from his mouth and a grin on his face, I know he was prepared - moreso than me, and that's perfectly fine. It gives me more fuel for later, and I'm sure many characters are on the same wavelength, provided every villain doesn't pop ye-old tooth capsule.