(The) Piper of the marsh CR 4
Source: Pathfinder #43.
CE persistent haunt (area T4)
Caster Level 4th
Notice Perception DC 15 (to notice the faint sound of mournful flute music and the eerie flapping of tiny leathery wings)
hp 18; Trigger proximity; Reset none (see below)
Once active, the Piper of the Marsh manifests as a disembodied, mournful dirge played upon a flute. The dirge can only physically affect those within the western cell-block itself—the halls facing one of the cells in the western portion of this floor. Each round, all living creatures (except for stirges) within this area must make a DC 14 Will save at the start of their turn to avoid being shaken by the effect.
Once per round on the Piper’s turn, one randomly chosen humanoid in the area is also targeted by a hold person effect (DC 14 Will negates)—those who fail this save not only stand motionless, entranced by the music, but also experience a vision of the ghostly Piper himself as he approaches, attended by a flock of stirges. Once a victim escapes this hold person effect, the cumulative effect of the fear caused by the Piper’s slow, inexorable approach forces the victim to immediately make a DC 14 Will save to avoid taking 1d6 points of damage as blood momentarily flows from a dozen tiny punctures that spontaneously open along his arms and neck. The Piper’s haunt may only target a specific creature once per day with this hold person effect.
Once the Piper’s haunt has been reduced to 0 hit points, it can not manifest again.