Maleficient is an evil witch on a quest for true immortality. Until she accomplishes her goal, she uses a midpoint form of magic called reincarnation in order to buy her more time and keep her alive. Reincarnation magic allows an individual to reincarnate themselves after death in the body of another human. Maleficient has a number of host bodies scattered throughout the world and trapped in a deep sleep to take control of in case she is killed by her enemies or dies of old age. Her most recent claim, a young girl named Snow White, is the next host that she will possess.
This spell takes a number of steps. After a person dies, their soul jumps into a magical item called a soul stone, which keeps the soul in storage and prevents it from crossing over to the next world. The soul is then transported and absorbed into the host body, giving the person possession over it. Reincarnation requires the victim to be living, so these hosts are placed in a coma-like sleep and kept in magical stasis to prevent them from aging. They are stored in this way until needed for further use.
The result is that the body now contains two souls within it that continue to remain separate, with the original soul remaining trapped and the dominant soul of the witch retaining control. The witch now has access to the person's memories, knowledge and spells to use. They can also access the person's mana for an extra boost in spellcasting if needed.
Powerful witches are likely to use this method to cheat death whenever possible, and limits need to be places on this form of magic to prevent constant overuse. To accomplish this, I have decided to make mana essential to the process. Mana resides in the soul, and its amount is determined at birth. For reincarnation to work, the potential host must have an equal amount, more or less, to that of the witch. In essence, individuals both weak and strong should only reincarnate themselves into others of their caliber. A witch might be powerful, but would have a hard time with this spell because there are few people walking around with that kind of power level. Alternatively, an average person would have an easier time because of a larger pool of individuals. However, this isn't a power grab. Even if they managed to take down a powerful opponent, transporting their own soul into them wouldn't be an option.
I need a valid reason for why this would be the case.
This spell takes a number of steps. After a person dies, their soul jumps into a magical item called a soul stone, which keeps the soul in storage and prevents it from crossing over to the next world. The soul is then transported and absorbed into the host body, giving the person possession over it. Reincarnation requires the victim to be living, so these hosts are placed in a coma-like sleep and kept in magical stasis to prevent them from aging. They are stored in this way until needed for further use.
The result is that the body now contains two souls within it that continue to remain separate, with the original soul remaining trapped and the dominant soul of the witch retaining control. The witch now has access to the person's memories, knowledge and spells to use. They can also access the person's mana for an extra boost in spellcasting if needed.
Powerful witches are likely to use this method to cheat death whenever possible, and limits need to be places on this form of magic to prevent constant overuse. To accomplish this, I have decided to make mana essential to the process. Mana resides in the soul, and its amount is determined at birth. For reincarnation to work, the potential host must have an equal amount, more or less, to that of the witch. In essence, individuals both weak and strong should only reincarnate themselves into others of their caliber. A witch might be powerful, but would have a hard time with this spell because there are few people walking around with that kind of power level. Alternatively, an average person would have an easier time because of a larger pool of individuals. However, this isn't a power grab. Even if they managed to take down a powerful opponent, transporting their own soul into them wouldn't be an option.
I need a valid reason for why this would be the case.