The Faller (8 HP, 2d6 damage [when possessing], invincible, immortal, possessing)
Instincts : To ruin, To murder, To rule
Fallers have no corporeal body. When they fall from the sky, most are destroyed or cursed to a mundane existence within an inanimate object. Some are able to steer their essence into a living creature, though, and gain agency by denying their host theirs.
A party will most likely encounter a Faller in the form of a wild animal who has become legend within a community for its viciousness, cunning, and wily evasion. (Source material to consider : Ghost in the Darkness, any werewolf story that focuses on the villagers) Occasionally a rash of murders in a city might be attributable to a Faller. These are particularly dangerous times, as finding and serving justice to the murderer will only delay the Faller until he finds a new host. Usually the guard or dangerous would-be-victim who would stop them, sometimes a gravedigger or priest who tends to the body.
When the body a Faller resides in dies, the Faller may transfer itself into any creature or person who touches the corpse. There is no visible element to the transfer, although the new host of all but the most experienced Fallers usually loses any accent or vocal affectations and develops a new gait.
Custom moves :
When you have a Faller inside you and make camp or rest, roll + CHA.
On a 10+ you drive the thing back and it holds no sway over you for now. Take + 1 forward to your next test against the Faller.
On a 7-9, the Faller (through the GM) will tell you to do something horrible sometime in the next day or so. If you do it, take XP.
On a miss, at some point in the next day or so you will blank out and come to having just done something atrocious. Take XP.