Magic works by utilizing the individual's mana to power a particular spell. These spells are designed to work through the use of either verbal enchanting or specific runes, which are used to activate them. Besides the one and done method, there is a way to extend the life of a spell. In this way, a spell doesn't have to end as long as the enchanting is continuous. The drawback is that these extended spells depend on the mana of the individual, which depletes over time. The more mana a person possesses, the longer the extension can last.
Years ago, a witch named Amelia Elizabeth Dyer ran a baby farm in which parents who couldn't provide for their children would pay her to take care of them in the hope that she could provide a better life for. Dryer took care of them in a different method, using this opportunity to kill the babies while making a profit, and killed over 400 children in her time. When she was executed, Dryer rose from her grave as a disembodied ghost. Now as a vengeful spirit, she continues to ply her trade, killing fetuses while they are developing. This has led to over 30% of pregnancies ending in miscarriages around the world.
Spells have been developed to combat this through the use of runes. Unfortunately, runes must be constantly active in order to be effective, using an individual's mana as a power source. Eventually, a person would have to deactivate a rune, or will have lost enough mana to reach dangerous levels.
How can mages extend these spells without causing the death of individual's using them?