I'm GMing Pathfinder 1e this weekend and my players will be delving through a cave that was once a silver dragon's lair. I want to have a bunch of encounters planned out so that I can stretch this crawl out to the end of session, since we have a guest player who we don't want in the story for too long or too short.
Stuff they will find so far:
-Group of Frost Giants in the entrance. They don't speak common, but are pretty chill guys if a player remembers to cast Tongues.
-SO MANY SPIDERS, while escaping down a spiraling cavern. I'll have them crawling out of the walls and stuff.
-A Black Pudding. Never used one of these, and I don't think my players would know what to do immediately.
-Long underwater cave with some aberrations in it, maybe gibbering mouthers. Also a gigas clam with a huge pearl to lure in the party ninja.
-Big ending surprise - it's not a silver dragon's lair, it's a black dragon's lair, and this whole plot was him luring you to get eaten. Why is this cave so long? Because the black dragon just uses his underwater secret entrance/exit for his schemes.
Party is level 10 and there will be 5 of them, 6 with animal companion. Does anybody know any good encounters for a group like this? Doesn't need to be system specific - I'd love ideas for cool cave traps and stuff.
I have a wildcard encounter idea:
A nonhostile (unless talks go wrong) run-in with what was thought to have been an extinct civilization, still speaking its language, having its customs, even wearing its history-known regalia. Whatever was supposed to wipe them out didn't get as far as a refugee group that took shelter in that dungeon, used its treasures and other resources to pick themselves back up, and have some semblance of continuity with what they had lost. Even more interesting if they truly don't know they're the last of their empire/kingdom/whatever left and their current leader was waiting for correspondence.