Unsurprisingly, the CR 3 hanged men are undead who wrongfully died by, you guessed it, experimental surgery.
Seriously though, they've got some rope-dragging tricks, but hanged men aren't anything to really write home about as-is. Eh.
Acid-spewing giant moths. Eh.
The undead apparition of one who died from extreme cold. It does pretty much what you'd expect. It is worthy of note, however, that there appears to be a bit of a Take That in the imagery: namely, the illustrated hoar spirit is that of an elven warrior wearing the stereotypical "chainmail bikini".