Our intrepid heros are travelling through mountain caves and cliff, when they are met by a rope bridge with many cave openings below both sides.You know where this is going.They start to cross and reach the half way point when hundreds of animated skeletons come boiling out of the side they came from and dozens come out of the side they are headed to.
If they wait, the close side will snap from the weight and they will be dangling with skeletons on both sides.Or do they cut it ?Combat ensues against the cliff face.
Additional Ideas (1)
Chase is given and the PCs encounter a crevasse. They have a small amount of time to figure out how to cross before the baddies in pursuit catch up to them. The lead baddie invokes a powerful necromancy spell and causes the dead who have been thrown in the crevasse (local funeral tradition) to rise up and form a skeleton bridge. Once the baddies are across many skeletons detach from the bridge and join the baddies as more expendable troops. Anything the skeletons kill is carried back to the crevasse army ant style. The lead baddie cannot control the undead, only guide them.