The Aurillian Shroud

Once per battle, at the start of either player's Command phase, the bearer can unveil the Aurillian Shroud. If if does, until the start of your next Command phase, the bearer has the following ability: ‘Aurillian Shroud (Aura): While a friendly BLACK TEMPLARS CORE INFANTRY unit is within 3" of this model, models in that unit have a 4+ invulnerable save.'