The deadliest power of the harpy was its insidious and captivating song. A harpy's song, while it was heard, acted like a charm affecting all non-harpies up to 300 feet (90 meters) away. It took an effort to will to resist; those who did could count themselves safe for a day, at least from that one harpy's song. In those who succumbed, it induced a trance-like state in which the victim was compelled to move directly towards the harpy. If dangers obstructed their path, they could shake off the effect, but if they could not, they could do little but try to protect themselves. However, once within reach of the harpy, the victim was at the harpy's mercy and made no attempt at defending themselves.