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Regeneration (also known as healing factor) is a term given when a particular character can heal from wounds at an accelerated rate, even regenerating from wounds that would be lethal to normal humans. Regeneration has different levels.
Low levels of regeneration are essentially just faster natural healing, so a wound that could take weeks to heal would take days, hours, or even seconds. More advanced forms of regeneration can regrow lost limbs, organs, going all the way up to regenerating from decapitation, being blown to pieces or vaporized, and even complete physical destruction.
Low: Faster healing ability for normal wounds.
Mid-Low: Able to heal wounds that would normally leave large scars.
High-Low: Able to regenerate some severed body parts like fingers, arms, legs.
Low-Mid: Able to regenerate limbs/fatal wounds. Still die from decapitation.
- Examples: Aaron Myers (Exceed), Shirou Emiya with Avalon (From Fake Dreams), Neptune (Starcross), Various Hallows (Monarchverse)
Mid: Able to regenerate from decapitation.
High-Mid: Able to regenerate from being blown into pieces.
- Examples: Samantha Fortepiano (Mirage Saga), Venus (Starcross), Hercules (SIEGE) with Apples of Hesperides
Low-High: Able to regenerate from a puddle/drop of blood, or a small piece of your body.
Mid-High: Able to regenerate from being vaporized/turned to dust.
High: Able to regenerate from a single molecule/atom/particle.
Low-Godly: Able to regenerate as long as your disembodied consciousness exists/regenerate from other realms.
Mid-Godly: Able to regenerate even after every aspect of the mind, body, soul, and consciousness, are erased from existence.
High-Godly: Able to regenerate even if your existence is erased and the reality you are within is destroyed.
- Examples: Tenebris (Kingdom Hearts IV), Chaos Phoenix (The Radiant Savior), Zavin Xcelua (Yuracion Absolon), Xero (Exceed)
True Godly: Able to regenerate from being erased on a level beyond the confines and concept of dimensions themselves.
To qualify for True Godly regeneration, a character must be able to regenerate from being erased from the duality of both existence and nonexistence, whereas it is only necessary to be able to recover from the former in order to warrant a Mid-Godly or High-Godly rating.