My focus in the whole thing is usually always the formula determination for generating the values.

An example A player has a Level 1 armor and then receives a Level 2 armor.
This can give the player to 50% chance max +3 HP Permanent, to 25% exists that this +15HP and to 12.6% max +40HP Permanent.
Now a formula must be generated from it that applies to each level up. so that an LVL 3 armor just gives 3 times etc...

What should be the formula for each level? can you help me? Please!