You keep using that word. I do not think it means what you think it means.

In all seriousness though, damage reduction has diminishing returns for armor and resistance, but effective HP does not. Same thing as in WoW because they are literally the same formula.

This shows that for V=1, 10 armor will give 20% effective HP. This is true at 50 armor. This is true at fifty million armor. In fact, it is both evident and true that effective HP will increase at a value equal to A/(A+50V) for all values of armor. This also holds for resistances because resistances follow the same form r/(r+5v).

If you want to talk about true diminishing returns, talk about the interplay between armor and resistances. It is factual by simple equation that +1 resist all = 10 armor = +10 intelligence. Because of the multiplicative interplay of these quantities, you are best served mitigation-wise to have resistances equal to one tenth of your armor value. If you have more than 10% of your armor as resistances, you should stack more armor. If you have less, you should stack more resistances.

You can extend the same logic to dodge chance technically (that it is optimal to have the same dodge% as your armor reduction and resistance values), but dodge is less reliable than solid resistance and armor for obvious reasons.

TL;DR: Armor and Resistance increase your effective HP linearly, not with diminishing returns. 50 armor at 0 armor is worth as much as 50 armor at 500 armor. It is most effective to keep your resist all at 10% of your armor (IE 5000 armor, 500 resist all), if you have more than 10:1 armor to resist it is more effective to stack resists, if you have less it is more effective to stack armor.

In all seriousness though, damage reduction has diminishing returns for armor and resistance, but effective HP does not. Same thing as in WoW because they are literally the same formula.

`Armor % Reduction Effective HP`

10 0.1666666667 1.2

20 0.2857142857 1.4

30 0.375 1.6

40 0.4444444444 1.8

50 0.5 2.0

60 0.5454545455 2.2

70 0.5833333333 2.4

80 0.6153846154 2.6

90 0.6428571429 2.8

100 0.6666666667 3.0

110 0.6875 3.2

120 0.7058823529 3.4

130 0.7222222222 3.6

140 0.7368421053 3.8

150 0.75 4.0

160 0.7619047619 4.2

170 0.7727272727 4.4

180 0.7826086957 4.6

190 0.7916666667 4.8

200 0.8 5.0

210 0.8076923077 5.2

220 0.8148148148 5.4

230 0.8214285714 5.6

240 0.8275862069 5.8

250 0.8333333333 6.0

260 0.8387096774 6.2

270 0.84375 6.4

280 0.8484848485 6.6

290 0.8529411765 6.8

300 0.8571428571 7.0

This shows that for V=1, 10 armor will give 20% effective HP. This is true at 50 armor. This is true at fifty million armor. In fact, it is both evident and true that effective HP will increase at a value equal to A/(A+50V) for all values of armor. This also holds for resistances because resistances follow the same form r/(r+5v).

If you want to talk about true diminishing returns, talk about the interplay between armor and resistances. It is factual by simple equation that +1 resist all = 10 armor = +10 intelligence. Because of the multiplicative interplay of these quantities, you are best served mitigation-wise to have resistances equal to one tenth of your armor value. If you have more than 10% of your armor as resistances, you should stack more armor. If you have less, you should stack more resistances.

You can extend the same logic to dodge chance technically (that it is optimal to have the same dodge% as your armor reduction and resistance values), but dodge is less reliable than solid resistance and armor for obvious reasons.

TL;DR: Armor and Resistance increase your effective HP linearly, not with diminishing returns. 50 armor at 0 armor is worth as much as 50 armor at 500 armor. It is most effective to keep your resist all at 10% of your armor (IE 5000 armor, 500 resist all), if you have more than 10:1 armor to resist it is more effective to stack resists, if you have less it is more effective to stack armor.