Rogue Trader: Pride and Profit
When rolling damage, if the unmodified roll of the d10 comes up a natural 10, there is a chance for Righteous Fury. Roll your WS or BS against the target again, using all the same modifiers as before. If the test is successful, roll another 1d10 and add that to the damage total before Armour and Toughness are applied. If the extra damage die also comes up a natural 10, test WS or BS again for an additional damage bonus. This can continue as long as natural 10’s are rolled.