The minds and hearts of children are becoming corrupted by a specific force. This force is able to use children because of their innocence, allowing vulnerable children to be kind of “infected” by this unknown force using Unholy Runes when can unfold in the mind of a child easier than they can in the mind of an adult. Children begin to act erratically and then violently. If left long enough the corruption will spread as the child grows into an adult and cause them to become aberrations over time. Characters must locate the source of the corruption and find a way to stop / reverse the corruption.
The entity wishes to grow in power, by drawing in children and corrupting them it can use the corrupted children as tools / soldiers while it seeks to corrupt more souls. The overall purpose will be to bring a larger demonic presence into the material plane the more worshippers and more chaos created in its name, the more power the entity will have.