Monster Regeneration is how a monster is born. Originally, the only ways to recieve a new monster were from breeding two monsters, combining two separate types, or by unlocking them from a mystery disc. But in recent times, other regeneration methods have become possible.
The regeneration of monsters is a recent phenomenon, but monsters themselves have existed from long ago. However, nobody knows why they were sealed in Saucer Stones, or when they disappeared.
- "Monster Mysteries" MR4
Tablet Regeneration uses words inscribed on the Monster Tablets to unlock the monster inside. This method involves typing in a password or phrase, sometimes given to you by in-game events.
Book regeneration (or Wiki Regeneration in the case of My Monster Rancher) allows you to record monsters that you have already unlocked by another means (disc, tablet, etc.) in your Encyclopedia for quick lookup and regeneration later. Since you often unlock the same monster type more than once, this method allows you to save the data from whichever one has the stats and traits you deem most valuable.
Incantation is a birthing method only used at BOMBA. A plethora of monsters are sealed away in the Grimoire. By facing the Grimoire and speaking out breeder's incantation, a monster will be released from its seal. Any words will do. Do what you can to release a monster from its sound seal. Breeders have to speak in their normal voice from about 8 inches away.