As Jeanne is burned, the faces of the villagers transform into Jeanne's, fulfilling a priest's warning that if a witch is burnt while her pride is intact, the evil in her soul will survive and spread to influence everyone around her.
Jeanne's burning causes the villagers' faces to transform into hers, as predicted by a priest who stated that if a witch burns while maintaining her arrogance, the evil within her will survive and infect everyone around her.