When a creature is required to give or lose blood, the amount is measured in [[Hit Point Dice]], a creature undergoing bloodletting follows these rules: - **Necrotic Damage.** The creature takes Necrotic damage equal to the maximum number of the Hit Dice required, if this damage would reduce the creature to 0 [[HP]], it instead drops to 1 [[HP]]. > **Example** > If a creature with d10 [[Hit Point Dice|Hit Dice]] must give 2 [[Hit Point Dice|Hit Die]] of blood, it takes 20 Necrotic damage. - **Expending Hit Dice.** To pay the cost, the creature must expend the required number of [[Hit Point Dice|Hit Dice]]. - **No Hit Dice to Spend.** If the creature has no Hit Dice remaining to spend, it may still choose to provide the blood. If it does so, it takes the Necrotic damage as normal, and its HP Maximum is reduced by an amount equal to the damage taken.