This can be earned at the first castle in Vampire mode. This is the last mode unlocked and gives you the ability to double-jump, has harder enemies that respawn outside the visible area, and drops health hearts when you throws any enemy. The following is a list of how much damage you take from each enemy of the first castle in Vampire mode, and how much health you can regain with the hearts they drop. Use those numbers to add and subtract from your health until you get exactly 1 HP left, then go to the save statue.

Blue skeleton: -6 damage, +2 health
Fire demon woman: -16 damage by touch, -10 damage by fire, +14 health
Gray/red fat man: -54 damage by touch, +49 health
Grey bomber with red bombs: -16 damage by touch, -33 damage by explosion, +9 health
Grey/blue zombie: -16 damage, +4 health
Pink archer: -6 damage by touch, -6 damage by arrow, +4 health
Pink bat: -6 damage, +2 health
Purple animated armor: -50 damage, +39 health
Wall torch (does not respawn): +5 health
Yellow skeleton: -10 damage, +4 health