Reverse actors HP MP progression

This is assembly hacking, so you'd need a hex editor. Hex Workshop is fantastic, but isn't free. My favorite free hex editor is HxD.

At C2/618F, you'll see 75, which is the hex code for the ADC (add with carry) instruction. To change that to SBC (subtract with carry), just change the 75 to F5.

The values I was referring to are the character's current max HP and the amount to increase it by at level up. These get added together at the location I specified and saved as the character's new max HP.