My suggestion is to either A) Default too or B) Add an option under conditions to use the formulas found here, specifically for the healing spells.

The formulas are here on the tibia wiki.
http://tibia.wikia.com/wiki/Formulae...mage.2FHealing

Right now I have these values in excel, but every few levels/magic levels these numbers change, so they would need to calculate dynamically. My goal is to set once and forget it.