Edit: Very similar problems to issues #499, #560, and #589 hopefully I provided helpful information.

Server Version: Paper 1.12.2

I'm trying to create an OP Factions server with 1.8 style combat and OP enchants. Ex. (protection.0-100) (sharpness.0-50).

While using this plugin once you have x>=protection.5 you take negative damage from anything above +4 Attack Damage.

Now this is when default is set "old_armor_strength = true"

Screenshots below if they can possibly provide some explanation that I don't understand.
Images 1, 1.a, 2, 2.a have "old_armor_strength = true" See config.yml: https://mcpaste.io/599ab873d279fbe8

IMAGE 1: Attacker using sharpness.50 sword.

IMAGE 1.a: Defender wearing protection.5

IMAGE 2: Attacker using wooden sword

IMAGE 2.a: Defender wearing protection.5

Below is a somewhat separate issue from above

I dont know if this is caused by the plugin or this is Minecraft but I thought I'd include it
Troubleshooting the issues I tried setting it to false. Everything worked perfectly when "old_armor_strength = false". Damage worked perfectly, but a different problem occurred; the difference in protection. Any x>=protection.5 isn't more effective Ex. if I enchant something as protection.100 it's no different than protection.5 (same with durability)
Images 3, 3.a, 4, 4.a have "old_armor_strength = false" See config.yml: https://mcpaste.io/ae4b7d15c9b2861e

IMAGE 3: Attacker using sharpness.50 sword

IMAGE 3.a: Defender wearing protection.5 (Armor Strength not showing here because I set it to false I'm assuming)

IMAGE 4: Attacker using sharpness.50 sword

IMAGE 4.a: Defender wearing protection.100 (Armor Strength not showing here because I set it to false I'm assuming)

As you can see, there was no difference in damage taken between protection.5 and protection.100

Thank you for actually providing some data, I will now have to do a lot of investigating and testing to figure out where the problem lies.

I've done some extra research after posting this which might help you or save time.

The problem is Minecraft's EPF cap or (reaching 100% protection) on armor/protection enchantments. EPF cap is reached when wearing protection 5 diamond armor.

When (EPF cap is reached) and (old_armor_strength = true) then, you CAN'T take damage because you're at 100% protection.

When (EPF cap is reached) and (old_armor_strength = false) then, you CAN take damage, but the damage you take doesn't decrease as protection level increases.

To fix: I imagine it has to do with overriding Minecraft's default EPF cap/values, but that sounds like it would bring a host of other coding issues like making an entirely new EPF curve or dataset.

But, that's why I just look for plugins and not create them, hope this helps lol.

Thanks for providing such detailed information, I will be looking at this shortly. Would you be available to perform some testing if I managed to fix the issue?

Yeah I could do that.

Any update on this yet?

I am currently rewriting most of the damage calculation system. It requires a lot of testing to make sure it is actually accurate.

@Jeklund6 please try the new test builds, where I have rewritten most of the calculations that deal with damage.

Closing due to rewrite of all damage calculation code. Please open a new issue with debug logs from the latest version if you think the issue is still present.

@kernitus I wanted to try making a server again and test your plugin, the problem I had persists. However I didn't feel like the need to respond because I started to get the feeling it wasn't your plugins fault it's just how the Minecraft EPF curve works and I don't know how to resolve that.