Pwnco is named for the rhyming verses she sings in order to gain entry. She can and will argue with you in quick-witted rhyme for you to let her into your home or kitchen. She loves nothing more than a good store-room snuffle and then to lightly terrorise the coursers around her with chasing, nipping, bad jokes and drunken dancing.

Her favourite time of year is as the weather gets colder, when she begins her visits, culminating in a series of absolutely huge parties between Christmas Day and Twelfth Night. She is dressed with ribbons, bells, decorations and is usually accompanied by an ostler, and other 'folk' characters like a jester and a Lady. Your characters may be pressed into taking one of these roles in her party.

When Mari gets to a house, dwelling or inn, they sing Welsh language songs or wassails, or more traditionally indulge in a ritual called pwnco: an exchange of rude rhymes with the person who lives there. If the Mari and her gang get entry, the household is said to have good luck for the year. The Mari is well-known to be mischievous, trying to steal things and chase people she likes as she goes about her bidding.