I'll try this one. It'd though require some expensive equipment, so I hope the current season will last enough.
I have some experience with the build, I hope this time I'll succeed.
I'll try Buriza to shoot immuns.
My skills will be:
20 Hydra (I like hydra as additional firepower and exploring ability)
The merc should be able to stand hits for me, and gather the mobs on itself, so I'll try A5 merc with Crainte Vomir + Rockstopper + Bered Leviathan for max. resistance. No idea if it'll work or not, but sounds good.
I reached some pretty cool levels, so I add my experience:
I didn't have Ravenclaw, so at the very beggining I attacked with any ranged weapons I've found, then switched to melee. It wasn't too bad, surprisingly.
My first weapon was Hellclap, then Kuko Shakoku. I currently use Demon Machine and Buriza. Didn't have the time to socket them yet (it requires patient to equip these, life is more important then equiping these as soon as possible).
Because of the lack of shield resistance is a problem at the middle-levels, so I suggest using Smoke. Surpringly during the beggining levels having max. resists is easy, so any armor do the job.
I was so fortunate to get access to a CoH, what is definitly a big help. But I plan on changing it to a Gladiator's Bane when I can cover the resists. The +skills are useful, but I don't think that much (I'd only loose 200 dmg accoring to the character sheet).
As soon as possible an Umed Shako is advised for extra life and resist and +skill. But with the new respec-system I'd like to try out Crown of Ages (it must be affordable in nonladder, what comes soon).
For boots I'd choose from Goblintoe in case you think it helps against the immuns enough, or go with resist-boot.
For amulet Mara is a fine choice.
For rings I suggest Bul Kathos for +skill and lifesteal (lifesteal helps), and a Dwarf Star (for direct +life and fire absorbtion). SoJ is a bad idea, its attirbs aren't useful for this build (warmth covers the mana-need easily).
Belt is Razortail of course, but maybe it worth to have a Thundergods against souls.
I have no real idea for gloves. Knockback would only have use against 1 target from mobs (and the eyplosion effect already do a similar thing) - this is true for almost all attrib you can have. Currently I use Bloodfist for fhr and +life. Gloves is pretty much a free choice.
For skill-developement I suggest starting with all points to Warmth, then to Enchant when it becomes avaiable. During this 1 point to frozen armor and teleport of course.
At lvl 30 start to invest into Fire Mastery, and 1-5 points into Hydra. Later 10 point into hydra while maxing Enchant and its syns. Finally maxing hydra.
My hydra currently do 1K dmg per hit, and you can put down 5, each has three heads - that's 15K damage per shot! And in places like Mephisto's temple, or Nihlatak(!) you can explore and kill from very safe distance!
From the remaining skillpoints here is suggested Cold Mastery to help Buriza's damage, but maybe Static Field would be bigger help to my merc.
My idea about the merc is to attract the monsters into one spot to make them an easy target. HF A2 merc would make them gather slowly, that's why I try out A5.
As weapon I chose Crainte Vomir for several reasons. The main thing is, the mercenaries tend to not focus their attack and try to deal out damage equally on each nearby target. So with Crainte the A5 merc will slow whole groups, especially as that sword is bloody fast!
The whole mercbuild of mine lacks lifesteal, so an Amn rune into the socket of the sword (by Larzuk) will be required.
If the merc will have enough resist, I'd try Gaze instead of Rockstoper for the additional lifesteal (and extra slowing from cold dmg ).
I currently could not afford fire skillers and other advanced charms, so my damage (according to the character-sheet) is between 5-6K with DM, and it is ok (this build wrks almost as a chain-fireball sorc, lol).