Battle Sister Squad

A unit with the Act of Faith special rule can attempt to use its Act of Faith immediately before it acts during a phase; i.e. immediately before the unit moves in the Movement phase, shoots (or runs) in the Shooting phase, or before any blows are stuck (either by friend or foe) in the Assault phase. To do so the unit must take a Leadership test. 

If the test is failed, nothing happens and that unit cannot attempt to use that Act of Faith again for the rest of the battle. If the test is passed, the Act of Faith is successful; unless stated otherwise, all models in the unit will immediately gain a special rule until the end of the current phase. The special rule gained will be listed in that unit's Act of Faith entry, along with which phase(s) the Act of Faith can be attempted in.

Unless stated otherwise, a unit can only attempt to use an Act of Faith once per game and a unit cannot attempt to use more than one Act of Faith in the same phase. A unit can only attempt to use an Act of Faith if it is entirely comprised of models with either the Act of Faith or War Hymns special rules.

Models with the Shield of Faith special rule have a 6+ invulnerable save and the Adamantium Will special rule.