Well, I've only use my Skelemancer for dclone killing so far, so this is all just ideas I'd look into if I had to use a sorc for dclone.
For a sorc, "cold" seems to be the only chance. Dclone is 95% resistant to all elements, but he's not immune --- so a maxed cold mastery will be of great help, and IIRC both fire and lightning mastery do not reduce the resistance.
In addition, a wand with lower resist charges can come in handy.
You will need a high damage spell, though --- since fire is supposed to be the tree with the highest damage, you might want to run the numbers first to see if the higher fire damage can compensate for the lack of -resist. I'd guess no, though.
That's the first thing --- damaging him. However, there are more problems than that.
DClone will not die to your first spell, he'll laugh at it. You'll be casting for a long time, so if all you can do is cast 4 times and you're out of mana... no good.
Also, DClone won't just sit there waiting for you to kill him. He'll come after you; and even though he looks like Diablo and behaves like Diablo, he's doing a lot more damage. His Armageddon rains down around him, though, so it's not your immediate concern. Still, you'll want the usual Diablo-setup --- high fiire and lightning resistance. Don't go for dclone if you're not handling Diablo well while you're drunk, asleep and falling out of your bedroom window.
Since you'll want to keep your distance, it's probably a good idea to clear out a reasonably large area before spawning him, so you can run around there freely. I have minions to keep him under control, but a sorc does not --- my merc always dies (he never dies to anything else, but dclone... it's a special case), and I suspect uber gear won't help him either. I may be wrong, though.
The last issue to be addressed is his healing. I've never actually seen him heal (my poison mages have more than 500 seconds poison duration...), but he's said to be healing extremely fast. So, you'll need some means to prevent that --- very fast very high damage so you can just ignore the healing, or some form of prevent monster heal --- which can be a problem. Check the uniques to see if there are any ranged PMH weapons, and hope that you can hit him
Or try a ranged weapon with poison over a long duration, using that to shoot at him in between your blizzards/orbs. If you haven't played an assassin, you might need to practice fast weaponswitching a bit (ok, martial arts assas switch skills not weapons, but it's about the same thing... they need to get into the right rhythm).
I don't know whether telekinesis can be used to "lock" a single monster in place, away from you and inside your blizzard...
As I said... just thoughts. I sometimes like to think about classes I don't play
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