- % to Enemy Poison Resistance only works on poison resistant monsters; it has no effect on immunities. Aside from lowering resistance, it also increases poison length; - 100% EPR will double poison length against practically every monster in the game, the sole exceptions being Ancients who get Poison Length Reduced by % from their magic equipment (- 100% EPR is also effectively Poison Length Reduced by - 100%).
Below is a list of all the poison immunities in Hell that are unbreakable by a Necromancer's level 10-61 Lower Resistance (- 55-70%/- 11-14% vs immunity), excluding random Possessed Champions with poison immunity (since they cannot be cursed):
Act I
120 Griswold
Act II
115 Devourers
120 Coldworm the Burrower
1000 Fire Towers; Lightning Spires
Act III
100 Water Watchers (cannot be cursed)
105 River Stalkers (cannot be cursed)
110 Stygian Watchers (cannot be cursed)
115 Undead Soul Killers
120 Giant Lampreys; Undead Stygian Dolls; Blood Wings
Act IV
125 Blood Maggots
200 Bone Prisons
Act V
115 Serpent Magi; Rancid Defilers; Burning Souls
120 Blood Temptresses; Unholy Corpses; Undead Stygian Dolls; Venom Lords
125 Achmel the Cursed *
130 Returned Archers; Cadavers
140 Horror Archers
1000 Catapults; Barricades; Barricaded Towers and Doors; Prison Doors
Pandemonium Event
140 Horror Archers
145 Pit Lords
* Achmel the Cursed has 50% poison resistance in all difficulties, so his poisonhit modifier (which isn't displayed) always gives him an unbreakable 125% (50 + 75) poison immunity.
Speaking of hidden modifiers...
The Ancients all have 50% poison resistance in Hell, but RTB informed me (and I have subsequently confirmed) that the Ancients spawn with magic equipment, which makes it possible for them to acquire hidden poison resistance and even immunity in two ways: Poison Length Reduced by 100+% (Korlic and Talic only); and 50+% poison resistance. Only poison immunity acquired from resistance can be broken by Lower Resistance.
Worryingly, if they get resistances and subsequent immunities from items, these are not displayed and do not count towards the limit of two immunities (which only applies to Unique modifiers). Worst case scenario: an Ancient could acquire fire, lightning, cold AND poison immunities in Hell from a combination of inherent resistances and immunities, Unique and item modifiers. :shocked:
Fortunately, this is highly unlikely, and even if it does happen, you can just open a Town Portal... which makes all this interesting, but ultimately academic.
