Mischievous poltergeist - ideas for an encounter?

[Monstrrr]

I'm still a new DM, and sometimes I get vague ideas that i am not sure how to flesh out.

I'm thinking about a silly encounter, kind of Scooby-doo in feel. A prankster ghost. It's a mischievous old ghost who tries to trick the PCs and trip them up. So, I'll set up traps that aren't designed to kill, just embarrass and annoy. Feathers, ooze, oil on the ground, all sorts of slapstick. Create some fun interactions with NPCs in the building that have been dealing with the ghost for a while. The NPC's of course would have been working on someway to trap the ghost, but they need the PC's help in order to implement it. By the time they run around activating various magical devices or drying runes on the walls or whatever i want them to do, they are covered in slime and feathers and have been thoroughly laughed at and chased around. Then in the end they have a choice as to whether or not they want to trap the ghost, set it free outside the university, or destroyed forever.

Any suggestions for how this sort of encounter might go?

[Wildarm]

Think haunted escape room.

Have the ghost make lots of spectral traps that will inflict lingering effects - Exhaustion, Stunned, Incapacitated(Asleep/KO), Poisoned, Restrained, Hindered. No HP damage but enough effect to have to react to the attacks making saves or attempting to hit their AC. Use lots of hazardous terrain and doom rooms to harry the party and funnel thing into specific locations without getting a chance to properly prepare themselves. Think rooms filling up with water, spectral boulders rolling down stairs, etc. Mix in some illusions and real world effects to really mess with peoples minds. Also a lot of fun, when the players step into the house for the first time, start a visible countdown on your phone for all players to see. Do NOT explain what the timer does but glace at it pointedly at times and give some doom like description of where they are as the timer gets lower and lower. Gives an escape room type feel and encourages players to hurry up despite better judgement(and run into more traps). If the timer runs out, they get ejected from the house it a wave of ectoplasm and essentially fail the mission.

Eventually the players will have to figure out a way to make the ghost visible/vulnerable and lure it to a prepared trap. Allow them to be creative and feel free to drop clues for them in different locations of the house. Let them fail forward so that whatever they are attempting has a reasonable chance of success. Perhaps they can appease the ghost. Give reasons why straight up killing it is not necessarily the best option. If it comes to combat be sure to capitalize on the fact that the ghost can phase into the ground and through walls. Have take the hide action a lot, zip in, do something tricky and zip out again. Players can ready actions but it will be difficult to catch the ghost if it's hidden and they cannot see it through LOS or hide action. Perhaps it's default invisible which also helps with this. Possession is also a good method for ghosts to use to really muck up a party.

Movies for inspiration: Monster House, Home Alone, Ghostbusters

[Monstrrr]

Also a lot of fun, when the players step into the house for the first time, start a visible countdown on your phone for all players to see.

I really like all of your suggestions, thank you! How long would you set such a timer for?

[Vogie]

Monarchs Factory (https://www.youtube.com/watch?v=RlHom7zSWD0) (Link to Youtube) has an excellent video on running ghost encounters.