As few warriors enter battle without the protection of armour, your opponent can make an Armour Save roll for each wound caused by your attacks. To make an Armour Save roll, roll a D6 for the wounded model and compare the result to that model's 'armour value':
If the Armour Save roll equals or exceeds the model's armour value, the model is saved by its armour and the wound discarded.
If the result is less than the model's armour value, the model's armour has proved ineffective and the wound is 'unsaved'.
Rolls of a Natural 1
Even the heaviest of armour can be breached by a lucky blow. When making an Armour Save roll (of any type), a roll of a natural 1 is always a fail, regardless of modifiers.