In the rule “Dragon”, replace:-

The Dragon’s Behaviour is to select a Knight at random from those which are not Wielding a Weapon or Shield (if any such Knights exist), and to remove half of that Knight’s Gold (rounding down). The removed Gold is then added to the Dragon’s Hoard.

With:-

The Dragon’s Behaviour is to select a non-Slain Beast at random (excluding itself) and to reduce that Beast’s Fortitude by DICE6. If this would reduce the Beast’s Fortitude to zero or lower, that Beast is instead Slain and “Slain by Dragon” is added to its rule. Otherwise the Dragon’s Hoard is increased by the result of the die roll multiplied by quorum. If there are no non-Slain Beasts other than the Dragon, this Behaviour has no effect.