A formula to provide diminishing returns on the HP growth you get from potions, which is currently unbounded.

In the formula, X represents the total amount of extra HP points you would have in vanilla (1 per blessed healing, 5 per blessed extra healing, etc), R represents the actual amount of extra HP points you will have under this formula, e is Euler’s number (a constant), and A represents the desired asymptotic upper bound of extra HP points you will approach:

R = (2A / (1 + e^(-2x/A))) - A

The value of A is up to the designer. If it’s selected as 100, for instance, total HP gains from potions will get closer and closer to 100 as more and more potions are consumed, but the hero will never quite reach it.