How to defense equate to HP and damage dealt?

"Dwinkelm;61113" wrote:
I've been seeing a lot of talking about the stealthed buff to defense/armor, or whatever we're calling it these days. A lot of the posts say something along the lines of "well an increase to defense by X% is really an increase to effective HP by Y%," or talk about the effective increase to protection. How are people calculating this?

Also, is there a more clear and concise definition for defense? If a character has 30% defense, does that mean they suffer 30% less damage from incoming attacks? Or is it more complex than that?

I've hunted around a little bit but can't find an adequate answer to these questions. All replies appreciate, thanks in advance!

Firstly, let's be clear about the terms. Defense covers both armor (physical damage) and resistance (special damage). If you have a mod which adds 10 defense (flat number) this will add 10 to both armor and resistance. Let's consider only armor in these explanations. Resistance works exactly the same but applied to special damage.

The armor flat stat is currently hidden, lets call this the armor rating. In your stats window for each character, you will see armor as a reduction percentage. This is an important concept to understand:
Armor rating is converted to a reduction % via a formula. We don't know the exact formula but it is clear that the formula is subject to diminishing returns. A character at 200 armor rating gains less damage reduction for each added point of defense than a character at 100 armor rating.

The flat armor rating can be found here: https://swgoh.gg/characters/stats/

Select the defensive tab and you can see the armor / resistance values for lvl 80 max geared toons.

How do mods interact with defense and damage reduction?

> Flat defense e.g. +10 defense, is added onto the flat armor/resistance rating which is then reflected as a damage reduction % by the above mentioned formula.

> % defense e.g. +11.25% defense, is calculated based on the unmodded flat armor/resistance rating. Again, this is reflected as a damage reduction % by the formula.

How does someone calculate effective hp taking damage reduction into account?

Suppose you have enough armor to reduce damage taken by 50%. What this means is that for any incoming damage, you can now take twice the amount of hits before you are killed. So this is (within reasonable assumptions) equivalent to having twice as much hp.

The formula to calculate effective hp percentage: 1 / (1 - dmg reduction %); in the above example = 1 / (1 - 0.5) = 2 or 200%

This means that whether I choose to have either 50% damage reduction, or add 100% hp, mathematically, the results are the same. This lets us perform a comparison as to whether defense or health is better for a given level of itemisation (e.g 5% health vs 5% defense).