Combat in Dungeons & Dragons is a lot of fun, but some of the best encounters I have experienced are actually very short. This can be down to player ingenuity; a clever use of a spell or a moment of tactical genius undoes the best laid plans of the big bad. It can also be down to the DM offering a simple solution to the encounter. If the players have been paying attention, they will solve the problem before it gets out of hand.
This is the kind of encounter I’d expect for the Kappa. An inherently creepy beast that could prove deadly for the less alert adventurers, that can be very easily defeated by the more knowledgeable explorers.
Kappa

A host of Kappa in a water-logged battle zone could cause a great deal of pain and suffering for a low-level party. With a turn spent studying their physicality, or a high roll on a Nature Check, the party could work out that these water-based demons have a comical weakness.
Just push them over and the fight is essentially over.
Thank You For Reading
You can find the rest of the Fantastic Beasts with D&D stats right here.