Faith Inviolate
Codex: Sisters of Battle, p. 5
When this Act of Faith is performed, the unit performing this Act of Faith increases their Invulnerable save from the Shield of Faith special rule to a 4+ instead of a 6+. If the unit already has a 4+ Invulnerable save, increase the Invulnerable save by 1 to a max of 3+. This lasts until the end of the Phase in which this Act of Faith was performed.