I was testing lining up a top-down map with an isometric map and created an encounter. I never got to using/testing it myself but thought I'd share. Let me know what you think!

Objective:

Retrieve the item inside the treasure chest.

Complications:

three teams are trying to accomplish this task.

GM only: one team is your players. The second team should be very aggressive combat-wise, potentially with some sort of grudge against the players. The third team prefers to go after the objective with searching and thieving.

the treasure chest requires three keys to open. 

GM only, lockpicking: by nature of the locking mechanism, it would require three people to all pick the locks at the same time to open the chest... all three players need to pass the lockpicking DC you set.

Four keys are scattered into the various pits that don't have the chest. Once in a pit, a player or NPC needs to pass an Investigation check to locate a key.

GM only: You can assign numbers and secretly roll a d6 to determine which pit doesn't have a key, reroll on a 6.

Pit distances are left up to the GM as part of setting the difficulty of the encounter. Falling damage in 5e is 1d6 for every 10 feet fallen, up to a maximum of 20d6 (200 feet).

the treasure chest itself is enchanted to be extremely heavy.

GM only: you may decide it is not so heavy that it is impossible to move. The chest can potentially be broken into; consider a fairly high HP value due to it's extremely sturdy construction and materials. An evil GM might instead roll to see if whatever object inside is broken after the player is given warning that they might break it. Also consider what level spell this enchantment should be at for the situation of whether a player casts 'dispel magic'.