Creatures can be reborn to level 1 for either a Credit or Coin cost to gain greater stats than a Superb. Currently this is a Credit Shop option that can be accessed here.
Please remember that Rebirthing will never turn a creature Superb quality. A Great at a Rebirth level of 99 will have .5 stat points lower than a Superb at Rebirth level 99.
A creature must meet the following prerequisites before it can be reborn:
Rebirth level will be added to the creatures quality during stat calculations. This can improve its base growth to a level even higher than Superb depending on its original quality. For example, you would have to rebirth a Great creature twice to have the growth needed to top a Superb.
For example, a Superb with a Rebirth Level of 5 will receive 5 points to each attribute at level up instead of 2.5 like a normal Superb.
The following things will happen to a level 99 creature if it is reborn:
A creature's tattoos and skills can be retained during rebirth if you acquire the Credit Shop Key Item Four Arms of Vishnu.
Please note that though this item will allow your creatures to keep tattoos, the tattoo effects will not activate until the creatures reach the minimum level required for them to be applied.
Extra skills are handled in a similar fashion. Until your creature reaches the required level again, you will not be able to access them.
This means that if a creature must be level 90 in order to apply a tattoo, that tattoo's effect will still not activate until the creature reaches that level.
The amount of experience needed to level up will increase by 5% per Rebirth level. So a creature that has a Rebirth Level of 5 will require +25% more EXP to reach level 99.