How does damage shield penetration work?

[jenx]

Say I have 80% damage shield penetration.

If an npc has 2000 shield, and I do 1000 damage, do I
1. bypass 80% of the shield (= 1600), and so I do 600 damage? (that is, 400 is blocked by the shield)
2. 80% of my damage bypasses the shield, so I do 800 damage?
3. something else....

Hope someone can explain.

And in addition
3. Does it work against all shields? Absorption shields etc?
4. Does having 120% damage shield penetration make any difference to 100%?

[HousePet]

Option 1 should be doing 0 damage, surely?

It is option 2.

3: It works against all Damage Shields. eg. the ones described as such.

4: No effect.

[jenx]

Option 1 should be doing 0 damage, surely?

It is option 2.

3: It works against all Damage Shields. eg. the ones described as such.

4: No effect.

Thanks.

With option 1 I meant, it skips 80% of the 2000 shield, meaning only 400 of the shield works. Thus my 1,000 damage does 600 (not sure why I said 1000 originally lol)

[jenx]

I've clarified the shields it penetrates: damage shields only, so time shield, displacement shield, disruption shield, doom shield, and abyssal shield are unaffected.