There are a great many spells that could be the key to an interesting encounter. One with particularly great potential is awaken. According to the spell it grants a 10 Intelligence to a single plant or beast under the right circumstances. It also allows plants the ability to move along with speech in one language. These effects are permanent.
Imagine applying the entire array of abilities to any number of beasts or plants. Not only can this spell affect expected beasts like horses, dogs, elephants and fish, as well as plants like trees and shrubbery … but also fungi and giant beasts. The only limit is a starting Intelligence of 3 or less and size of Huge or less, and the beast or plant creature type. It is worth noting awaken is an expensive spell to cast, requiring an agate worth 1000 gp, which the spell consumes.
This awakened beast or plant could fulfill multiple roles in your campaign or encounter. Since it has average human Intelligence, human-like senses and can speak a language, you could run this as a roleplaying encounter in addition to a combat or puzzle encounter. This beast or plant could be a full NPC or companion to another NPC. In this case we’re aiming for a social encounter, but also a more specialized version of a social encounter because the NPC in question is an awakened tree with a service to offer.
For this encounter to work, you’ll need a forest of a decent size, and hard to traverse for more reasons than just having trees in it. Treacherous gullies, jutting rock formations or even a forest on a steep incline of a mountain are all valid choices. Feel free to use these or any others you might think of. The awakened tree acts as a way to connect two parallel roads at different — and difficult to access — elevations. This encounter arranges travel through difficult terrain that would otherwise slow, hamper and endanger the party. If those conditions are met, insert something akin to this in your world to engage players and turn a travel situation into a rich opportunity for roleplaying.
Encounter Type: Social
Map: Deep forest map
Lighting: None (flat battle map.)
System: 5E
Length: One shot
Installation Type: Addon
License: Roll20 End User License Agreement
(Personal Use Only, Do Not Distribute)