Rusalka

A girl who died in the river unmarried, unmourned or both does not rest. She becomes a rusalka, a pale maiden with weeds in her hair who sits on the bank combing it and sings until someone comes close enough to pull under. Her song on the board does exactly that: it drowns a single enemy slowly, and the cold of the river slows everything it touches. She is already half spirit, which is why blades pass through her as through mist.