Enemy cold resistance: -115% Break Immunities?

[kwfp]

can I break cold Immunities by opgrading this skill to +20 "- Enemy cold resistance"

How good will it work?

If not.

Is it possible to break immunities on all cold monsters maybe with something called infinity?

Thank you!

[Nimbostratus]

Only Lower Resist (necromancer curse) and Conviction (paladin aura) can break elemental immunes. When working against immunes, both effects are cut to 1/5 effectiveness. Most cold immunes are unbreakable even with the Conviction provided by Infinity.

[Davio]

Cold and Fire (poison too?) immunities are impossible to break, lightning is the only breakable one because lightning immunes have only like 120% resistance whereas the other elemental immunes have more like 300 resistance.

[sirpoopsalot]

actually, it's not that high - it's just because of the 1/5th penalty that they're essentially unbreakable.

Most:
Lightning & Poison monsters: 100-110 (100 is probably the most common)
Fire: 110-130 (120+ is probably the most common)
Cold: 150+ (most are higher than 150)

... since Infinity's conviction gets cut to 1/5th effectiveness (from -85% down to -17%), lightning is the only element that Infinity is really viable for (Conviction doesn't lower poison resistances; only Lower Resist lowers Poison resists).

If you run with a level25+conviction paladin, you can effectively remove a lot of fire immunes too (in which case, Infinity is fairly useless since it's aura gets overwritten by the paladin's). Or if you use Lower Resist charges on a wand in addition to the Infinity, you can break a reasonable number of fire immunes, but this approach is really a pain in the butt, and the monster will still be very highly resistant, so either approach here can be considered barely viable.

And if you add a very-high-level Lower Resist necro to go with that paladin, you might have a chance of breaking an occasional Cold Immune (I wouldn't count on it though). That's the one element that you might as well consider truly unbreakable.

[mephiztophelez]

Ernir's Things you SHOULD know about D2. Section 2. (http://www.battle.net/forums/thread.aspx?fn=d2-general&t=1312543&p=1&#post1312543)

2. Can immunities be removed?

Yes, they can. Monsters immune to a damage type are classified as monsters with 100 or more percentage resistance to the damage type in question. If you lower the monster's resistance below 100%, you can damage the monster.
There are only two things that can remove elemental immunities: The Paladin's Conviction aura, and the Necromancer's Lower Resist curse. Conviction Aura also doesn't affect Poison resistance. The Necromancer curses Amplify damage and Decrepify can remove physical immunity.
All other types of -resist (Facets, Cold Mastery, Griffon's Eye) do NOT have an effect on immune monsters.
Also, all the spells mentioned above work at 20% efficiency when dealing with immune monsters. Example: A hell Doom Knight has 110% Fire resist, meaning it is immune to fire. That Doom Knight is hit by a level 3 Conviction Aura, which under normal circumstances would lower the monster's fire resistance by 40%. However, since the monster is immune, the Conviction aura only works at 20% efficiency, making those 40% in effect only 8%. The calculation is: 110 - 40*0.2 = 102 fire res, making the monster still immune.
This fact makes it much harder to break immunities. There are monsters whose immunities are simply impossible to break. Hell Oblivion Knights, for example, have 180% cold resist. Doesn't matter what you throw at it, it is impossible to break.
Even though you can combine Lower Resist and Conviction (the resist reduction percentages are simply lumped together and the combined number reduced to 20%), any resist >= 145 can not be broken, even with a Level 25 Conviction (-150% Resist All) and a Level 60 Lower Resist (-70% Resist All). Thanks to Technomage-C01 and BIGeyedBUG for pointing that out, and Tommi and Adeyke for the information.
-res from items and other skills are not completely useless when dealing with immune monsters, though, because once the immunity has been broken, these items take effect.
Physical immune monsters are monsters with a physical resistance of 100 or more. This immunity can (as mentioned above) be removed using the curses Amplify damage (which gives -100% physical resist) or Decrepify (which gives -50% physical resist). Again, the same penalties apply to Amplify Damage and Decrepify as to the elemental immunities.

You can look up monsters' resistances here:
http://www.battle.net/diablo2exp/monsters/
(http://www.battle.net/diablo2exp/monsters/)