Command Reroll

Any phase, just after you make an Advance roll, a Charge roll, a Desperate Escape test or a Hazardous test for a unit from your army, or a Hit roll, a Wound roll, a Damage roll or a saving throw for a model in that unit, or a roll to determine the number of attacks made with a weapon equipped by a model in that unit.
You re-roll that roll, test or saving throw.
"By the Emperor, it will be done!"