Niamh is different from all our other Characters. Born on the streets, raised by thugs and grave robbers, this is a woman with a thousand faces and a real jack of all trades.
She has no basic deck. Instead, she can use any of the basic decks, picking any of four general archetypes, and enter any campaign. She gives you more flexibility when putting your party together, and can close any gameplay gaps you have.
She also comes with her own board, and 30 unique upgrade cards for combat and diplomacy. Her Streetwise ability is just as useful, letting her slip in and out of Settlements unmolested, as long as she’s alone. Of course, there’s also a drawback. Niamh is quite notorious in many places. As such, she has a significant Reputation penalty that extends to everyone who travels with her.
—description from the publisher (edited)