Decoy Corpse

Biology(?)

Did something just move over there? Was that body there all along? Nothing is scarier than not knowing, or even fearing that there is something stalking you, just waiting to lash at you. The Decoy Corpse, often simply called Decoy, is a strange shapechanger that few people have heard of, and even fewer have seen and lived to tell the tale. Its name is derived from its ability to assume a dead form to hide when observed. Not just the form of a dead person, but a form that is actually truly dead. It shows no signs of life and even magic detects it as dead in this state.
The origins and nature of its being are contested. Some believe them to be formerly people or resentful undead spirits who did not transition well and were caught between two quantum states of being. Both alive and dead, they only act as the dead they are when observed, or that's the theory at least. Regardless, through experimentation done in Ryvallen it is known (by however few at least) that the change in form seems near instantaneous and cannot be bypassed through any form of scrying magic either. The corpse form is a literal corpse, and any damage done to it is not transferred to the Decoy's true body. When it is no longer observed it instantaneously reforms, no matter how damaged, burned or torn apart it was. Regardless, even if the true form is damaged or killed whilst unobserved, it will still revert to corpse state once looked at, which poses an interesting question: How can one ever possibly know for sure whether or not the thing is dead, or simply playing dead?
Its true form is rather unknown and even the most powerful of divination magics shows only a fuzzy outline of something lanky with some form of sharp appendage. This can also be seen from the wounds on any of their victims, who usually display lacerations as well as bite marks and chunks of missing flesh, indicating some carnivorous need or desire to eat flesh.

Intelligence and Social Behavior

Little is known about their emotional intelligence, as the Decoys do not speak or even communicate in any way, even if the body they have hijacked would be perfectly capable of doing so. What intelligence there may be is theorized to be either malevolent or wrought with resentment, as they almost universally act as merciless killers. It usually starts with only a single kill, but they stay near the site pretending to just be another victim, waiting for more potential victims to arrive. Patiently biding its time, until everyone turns their backs to it and it may strike once again.

Statistics

(Credit to u/IAmTheOoga)

(Decoy in Corpse form. This is not anywhere near to its true form.)

Geographic Distribution

• Eastern Steppes
• Middenland
• Sabara