Basic Information
Literally "growing again", regeneration is a term used to describe the sort of superhuman healing ability that allows you to re-grow missing limbs and organs as well as closing up ordinary wounds.
In real life so species - mostly reptiles and amphibians - have a limited ability to re-grow limbs (indeed some lizards use a detachable, sacrificial tail as a defence mechanism), but this ability is fairly rare and generally limited to external structures
In most fantasy and sci-fi regeneration is also faster than normal healing and allows the user to rapidly shrug off any injury that isn't immediately fatal - indeed in some cases their regenerating powers are so formidable that they cannot be killed by any attack that cannot somehow prevent regeneration. Fantastic regenerators are also often able to re-attach severed limbs by holding them to the stump and waiting.
The ususal means of overcoming regeneration involve attacks that dissolve and destroy tissue rather than merely cutting through it - killing it with fire is the traditional method, although corrosives also usually work and by extension radiation, poisons and disease should work as well1. In some interpretations, this is how silver does for a werewolf. If all else fails, trapping the creature somewhere and killing it with hunger, thirst or suffocation should work. It may even starve faster if forced to regenerate a lot.
In a realistic campaign (or at least as realistic as you can get with regenerating creatures in it), radiation might be a particular weakness of regenerators2 - the implications of developing a cancer when your cells already proliferate at an alarming rate and are very hard to kill don't really bear thinking about.
Regeneration in RPGs is often a characteristic of specific species - blob monsters of various kinds are favourites as, for some reason, are trolls. If it's added as an afterthought, rather than as a characteristic of a species a healing factor may be at work.
It's also common to discriminate between the "rapid, unkillable healing" versions, the "slower, but still unkillable", "fast (or slow) if not killed" and the artificially induced medical3.
Some regenerators may also leave autonomous body parts lying around when they get bits chopped off. If the chopper off is lucky they will be sacrificial decoys like a skink's tail … in the worst cases the parts will violate conservation of mass completely and re-grow a complete creature from the severed part as well as the original creature growing back what it lost4.
Sources
Game and Story Use
- Older than print for boss monsters - Heracles found this to be an annoying characteristic of the Lernaean hydra.
- Can make a moderately annoying monster into an unkillable menace.
- Also useful for the Jason style unkillable slasher.
- For solo RPGs, can keep a PC alive and kicking.
- For a darker setting, a regenerating monster could be a useful source of power components for alchemy. And because it regenerates …
- In the same vein, more sadistic villains could indulge in the endless vivisection without the scientific curiosity.
- There was also a remarkably cheerful WHFRP module in which a colony of cultists fed themselves by repeatedly eating slices cut from one of their number who happened to regenerate.
- In real life, anyone demonstrating this sort of superhuman power has just won a one way ticket to the secure areas of Porton Down (or national equivalent). As discussed in Heroes this is a talent you want to keep really quiet about.