PSA: Armor and MR do not have diminishing returns.

**Diminishing returns is when you specifically receive less of a value for every instance of that value. **

In the case of armor/mr you are simply seeing the effect of scale. Just like 600 HP is +50% of 1200, but another 600 is only +33% of the 1800 you now have.

---

There is no soft cap or diminishing returns for resistances.

If you have 3000 HP, buying 180 doesn't seem significant. Its the same with armor.

If you have 3000 HP and you have 300 armor, you have 12000 Effective Health Points (EHP) vs physical. Buying another 100 armor gives you another 3000 EHP vs physical damage. Absolutely no diminishing returns involved.

Armor is the same as HP, just represented in a different light.

If you don't think you get diminishing returns from the flat HP you purchase, you do not get diminishing returns from armor either. You are buying flat 'EHP', where each point of armor supplies equal 'HP' to 1% of your actual HP in total health vs that damage type.

{quoted}

All reduction/division values can actually be pretty missleading and confusing with how they're written. It's easier to look at armor as fractions when considering what the OP is talking about:

100 armor is 50% damage reduction, 50% damage taken, or 1/2 damage taken. 200 armor is 66.67% damage reduction, 33% damage taken, or 1/3 damage taken. 300 armor is 75% damage reduction, 25% damage taken, or 1/4 damage taken. 400 armor is 80% damage reduction, 20% damage taken, or 1/5 damage taken.

If you have 1000 HP, getting another 1000, 1000, 1000, 1000 is going to do the same exact thing as taking 1/2, 1/3, 1/4, and 1/5 damage from armor.

This is very much linear scaling, not diminishing returns. Diminishing returns indicates you'd need more and more armor to go from 1/2, 1/3, 1/4, 1/5, etc. jumps rather than the same value (100) being between each increment.

---

The % damage reduced tooltip is very misleading and is causing way too many people to mistake efficiency with diminishing returns.

Buying health becomes more efficient at certain thresholds, just like armor/mr is more efficient than health at certain thresholds. This is efficiency of your purchases, not diminishing returns when you make an inefficient purchase.

---

TL;DR: You are not buying a % reduction vs that damage type. You are literally buying HP that is only effective vs that damage type. However, rather than the base unit being 1 HP, its 1% of your max HP.