Mari Lwyd

A skeletal mare speaks in constant rhyme, its jaws moving as if something were puppeteering it._
Unwelcome Lodger. A mari lwyd seeks entry into a home, where it demands to be treated as if it were a guest. Though it doesn’t require food, drink, or sleep, it consumes as much as a horse of its size and requires bedding that is comfortable, clean, and large enough to suit its frame. Despite its apparently baleful nature, the mari lwyd does not seek to harm its hosts, physically or financially, and demands only what they can comfortably provide. It defends itself if attacked, reciting rhymes beseeching its hosts to calm themselves.
A mari lwyd may accompany itself with a “retinue” of skeletons. It refuses to animate zombies, because it doesn’t wish to trouble its hosts with the smell of rotting flesh. It also politely refuses hospitality on the behalf of its cohorts.
Expelled by Rhyme. Other than through its physical destruction, the only way to rid oneself of a mari lwyd is to win a rhyming battle. It speaks only in rhyme, often changing languages for the best rhyme scheme between verses, which may provide a clue to those inconvenienced by the mari lwyd. It is especially appreciative of clever rhymes. The mari lwyd usually incorporates winning rhymes into its repertoire. Should a mari lwyd revisit a location, the inhabitants must come up with an even better rhyme to oust the creature.
The mari lwyd takes more conventional methods of turning away undead as an affront. If affected by a cleric’s turning attempt, it leaves for the duration and waits for the cleric to exit the premises before returning and increasing its demands for hospitality.
Undead Nature. A mari lwyd doesn’t require air, food, drink, or sleep.