Act 4 hell uniques problems

Question

I am playing a single player meteorb sorceress and I can not complete Act 4 on hell. To access Diablo, you need to kill 3 uniques, Infector of Souls, Lord de Seis and Grand Vizier of Chaos. Now, I have faced them two times already, and both times they were immune to both fire and cold. My defensive merc from nightmare act 2 cannot deal with them either, since they heal faster than he damages them (or at least Infector of Souls does). I tried hiring the lighting merc from Act 3, with no success.

So, what do I do? Is there are chance that they spawn differently, not immune to both fire and cold?

EDIT Well, having watched this video, I realized that the way to go is just to save and exit and try again. It's not necessary that the uniques have both resistances, it's random. I got lucky on the fourth time :)

Answer 1

As you mention, the immunities can vary and "rerolling" the monsters can result in better options.

The Infector of Souls in Hell has base elemental resistances (see d2wiki) 150% Fire, 70% Cold, 95% Lightning. So he'll always be Fire Immune. Each game, the various bosses get randomly assigned modifiers. The Infector always gets "Spectral Hit" and "Extra Fast" and in Hell, he gets two additional randomly-selected modifiers. If one of those is "Cold Enhanced", that boosts his cold resists by 75% (see d2wiki)which puts them to be more than 100% so he would be also Cold Immune, which is a problem for Meteorb builds unless they have a really strong merc. It sounds like that or something comparable happened the first time you tried.

Another option is to carry a wand with Lower Resist charges to remove immunities, but depending upon how high the resists are, that may not work. The expensive ladder-only "Infinity" runeword gives the Conviction aura, which can also break some immunities (and increase damage dramatically for nearly immune monsters.)

You may have better luck with a Might Act 2 merc (offensive from Nightmare) rather than a Defensive merc. With a decent weapon, that may be better and you should be able to Static Field them to halfway to help your merc along.