Can lightning immune lister have his immunity broken, including infinity? Is there a -light% to reach to break it, or is he just straight up immune if he's immune?
Lister the Tormentor has 2/11 (~18.2%) chance of spawning Lightning Enchanted in Hell, but only 17/110 (~15.5%) of becoming Immune to Lightning: Magic Resistant LE and Cold Enchanted LE make him Immune to Cold first, while Stone Skin LE makes him Immune to Physical first.
When Immune to Lightning Lister always has Lightning Resist 128%, which cannot be removed with an Infinity polearm's Level 12 Conviction Aura When Equipped (LR -17%) and level 3 Lower Resist charges (LR -8%). However, it
can be removed by a Paladin's level >23 Conviction.
Light sorcs/javazons and are big baal runners, so I figure it can be broken. Isn't there no monster who's LI can be broken? Or only a handful or something.
No monster in the Throne of Destruction can be both Immune to Physical and Immune to Lightning at the same time, and the only normal monsters Immune to Lightning are Burning Souls. Although Burning Souls have Damage Resist 90% they only ever have LR 100%, so their lightning immunity is easily removed (they already have two immunities, so their lightning immunity never increases, even when LE).
This means a Lightning Amazon or Sorceress can kill anything bar the occasional Unique or Super Unique, which a Desert mercenary equipped with an Infinity polearm should be able to kill. A Lightning Amazon can apply damage other than lightning to assist, while a Sorceress can cast Telekinesis to make life easier for her mercenary (even though there's only 35% chance of it applying Knockback).
Consult the Amazon Basin wiki's
Immune to Lightning page for what should be a complete list of monsters guaranteed to be Immune to Lightning in Hell: the list of normal monsters with LR >115% is very short, and that of monsters with LR >120% is even shorter.