In some genres, especially superhero, villains may be defeated, but this is rarely permanent and they will return again to trouble the heroes once more.
This supplement lists 25 different ways in which a villain (or perhaps a hero) could have survived an experience that looked like it was surely fatal. Some may require a degree of retcon, as they reveal previously unknown abilities; others may change the character of the villain and their abilities to differing degrees.
Here is a sample result:
"Your attack would have killed a normal human, but not my Robotic Body!"
The supposedly deceased villain was not actually human, or organic, in nature, but instead was a very lifelike android or robot. If previous scans or probes had apparently shown them to be human or, at least, biological in nature then it would follow that their body possesses some means capable of fooling such scans or probes. The attack failed due to the villain's body being constructed from artificial materials much stronger than mere flesh and blood.
One page of the supplement is the cover, one page the front matter.