Bloodthirsty Shiver

At the start of the combat phase, you can pick 1 unit from each Bloodthirsty Shiver in your army. If you do so, until the end of that phase, if the unmodified hit roll for an attack made with that unit's Ferocious Bites is 6, that attack scores 2 hits on the target instead of 1. Make a wound and save roll for each hit. If the attacking unit is within 3" of 1 or more other units from the same Bloodthirsty Shiver, its Feorcious Bites scores 3 hits on an unmodified hit roll of 6 instead.