On Saturday I'll be running a session for a party consisting of a 3rd-level cleric, a 3rd-level fighter, and a 3rd-level rogue. A dozen bandits (a 1st-level fighter, a 1st-level rogue, and 10 1st-level warriors) are going to raid the small village that the PCs are in (which only has a watch of 6 1st-level warriors and a 1st-level fighter as a guard captain). I already have a variety of combat encounters worked out, but I do not want the entire session to be hack'n'slash.
I need a few ideas (3 to 5) for skill-based non-combat encounters that can happen during the raid (such as saving a child from a burning building) along with some rough mechanics for them.
You could have the roguish character attempting to do things behind the scenes that disrupt others actions (the sneaky thief rushes in to attempt to steal things from the inn the players stayed at, potentially causing them to track down the rogue back to the bandit camp, causing them to attempt to deduce these things from what has been given. Thing such as muddy footprints, or perhaps a particular trademark these bandits have. Alternatively, perhaps the rogue is there before the rest, acting as a scout. The PC's might be able to notice his strange actions, potentially catch him and question him.)
Tyrantherus is onto a good idea with possibly questioning the rogue.
You could make several clues prior to the actual raid happening that it's imminent.
There could be a diplomacy gather information check to reveal that the raids are hitting closer and closer to town and the last merchant caravans are keeping all their juicy juicy goods-carrying wagons inside until they move on. Further investigation reveals that there are no other likely targets for the bandits to hit, and they are probably feeling very confident.
Let's say they make a perception check to see the rogue leaving town, alone, from a town practically besieged by bandits. That's suspicious. Let's try to catch him and interrogate him. Even if they don't, maybe they could find out who he was talking to. They trace his steps to a guard, who sense motive shows is suspicious. A bluff/intimidate later and they have the traitor, or if they don't handle it well, now the guards AND the bandits think they're the enemy.
Three clues is usually a good target. Maybe they intercept a shipment of weapons that a crooked merchant is trying to buy protection with? Maybe they find a town of likable people with amusing foibles and have to convince a slightly higher level inquisitor-type that he doesn't need to put the screws to the village over rumors of an upcoming attack because the party has it handled. Maybe they uncover the background of the bandits, that they got kicked out after an intra-family feud and have settled scores with all the merchants that wronged them and only have the people in town left to deal with. All good possibilities.
Then you can have them make preparations to deal with the attack. Talk tactics with the guards. You have to impress them with your leadership somehow. Maybe build a few traps. Maybe rally the peasants. Stuff like that.
This way you have a balance of combat/non-combat, and you use them to reinforce each other, with the non-combat plot elements built together to reinforce the capstone battle(s) as meaningful encounters the party has an investment in the outcome of.
Your cleric can try to rally cowering villagers to help defend the village. The fighter can direct the defense (do they have warning the bandits are coming? They could fortify the village.)
Maybe the bandits are after a specific treasure hidden in the village. It is locked away and the only person with the key and knowledge of the traps guarding it is not around, so the thief has to get to it before the bandits reach it.