I am playing a Pathfinder campaign based on the Beginner Box materials. The party were relatively diplomatic in the first adventure and didn't fight and kill the goblin boss King Fatmouth in Black Fang's dungeon, so I will have him return leading another band of goblins.
As well as specific equipment/strategies to escape (e.g. smoke bombs), what are some less obvious ways (particularly improvising equipment or the environment) to, as a GM, plan for an NPC villain to avoid dying in a combat or leave their fate ambiguous?