I've noticed some confusion about how a Sorc's EnergyShield works, maybe since ArreatSummit incorrectly shows that damage is diverted with EnergyShield before any is sent to BoneArmor or CycloneArmor (though it would be cool if this were the case). Below is some information with examples for HUv1.7.
I'm pretty sure this is the correct order of steps between being targeted by some attack and losing HP:
- Armor. Regardless of your AC, there's at least a 5% chance to hit you and at most a 95% chance to hit you. Your AC is considered zero while running. Your level plays a very large role in determining if something will hit you.
- Block. Your %Block is reduced to 1/3 while running. In HUv1.7 Blocking is capped at 66%.
- Dodge/Avoid. In HUv1.7 these skills max at level 10 so you could expect a 58% chance to dodge an attack after +Skills. PureRage edited the Dodge animation from 6 frames down to 4 frames to reduce dodge-lock.
- BArmor/CArmor. You've been hit, PhysDamage goes to BArmor and ElementalDamage goes to CArmor. When those armors are destroyed then extra damage continues down.
- EShield. Some of the damage is steered towards mana, the amount redirected is labeled "Absorbs X%", and is capped at 66% in HUv1.7. For the damage sent to mana, you normally lose 32 MP per 16 damage (i.e. 2MP/1Dmg), this is shown by "X/16 Drain Mana", and is capped at 8/16 (i.e. 1MP/2Dmg).
- PDR/MDR. These play a small role reducing damage from large hits, and a large role from small hits. The Physical Damage sent to your HP can be reduced by PDR "Damage reduced by X". Fire, Lightning, Cold, and Magic damage can be reduced by MDR "Magic Damage Reduced by Y". In HUv1.7, if the X and Y in PDR and MDR are the same, then it is described as "Non-Poison Damage Reduced by X" because only poison damage is unnaffected. HUv1.7 is balanced so that negating 33% of TrashMonster damage is pretty easy, so a build with high-quality EShield can easily become immune to TrashDamage at this step.
- Resistances. Resistances play a large role reducing the damage from large hits, and a small role from small hits. These are capped at 50% in HUv1.7, but it is possible to raise that cap to 66% via skills and items.
- %Absorb. Absorbs are capped at 40% (i.e. you can never be healed via %Absorb), but in HUv1.7 it should be pretty hard to get more than 25%-33%. In HUv1.7 Absorbs are never lowered by curses or auras (unlike resistances).
They act in two steps:
- Resist a % of the damage like a Resistance would. If the unresisted damage is enough to kill you, then you die.
- If you're alive, then add that % of the damage back to HP.
- +Absorb. These are not capped, but have never been featured in HU. I assume they function in the same 2-step process as %Absorbs. I've had characters back in Vanilla that were healed by enemy flame spells since there is no cap on Absorb.
- Damage now reduces your HP. DamageToMana effects convert some of the HP lost by Physical Damage to MP. HP lost by Melee Physical Damage can be reflected as physical damage by %Thorns. In HUv1.7 monsters do about 3% of their HP as damage so 3000%Thorns would cause them to die from a single attack (however many monsters do not do all of their damage as physical). If your HP goes negative at this step then you die, but there is an old D2 bug where ShapeShifted Druids simply revert to human form with 1 HP.
If folks know more about the steps above, feel free to add information. I was testing a bit with ShiverArmor and ChillingArmor, and would guess that they counter-attack before step 1. Item onStruck procs seem to occur before step 4 (damage calculated).