Hi Shivera, thank you for the thoughful and in depth reply. I understand the scaling drop (although very bad game design with no tool tip that says that anywhere where to player to see in-game). And even then that would mean when you deal 1M damage to a boss you should always then be a full health which you are not.
Anyways, my point in illustrating this example to the original poster is simply that the game developers do not scale things well with HP. And if the easiest and most literal text examples of % life are not scaling properly, other things are likely not going to scale with HP.