The amount will be calculated from the actual deduction of the HP and not the damege itself.
Example: If the HP of the enemy's fighter is 10,000, and the amount of damage is 100,000 during the damage reflection was increased by 30%, The 30% from the actual deduction of 10,000 will be the damage reflection.
Additionally, you cannot defeat the enemy by the damage reflection.
With this, the HP will remain as 1.