Chaos runs, with any character viable and that you think is fun. Frostmaiden, if you can afford it, is my recommendation. Fun as hell. There is cold sorc, combined with high level static field if you're on budget. Static for non lightning immunes and bosses, yes only works to 50% hit points, but works very quickly to that level. So in my opinion it's worth it. Unless you can make the cold damage so high that they die very quickly.
Bowa is another .. can be made to work on slightly higher budget level. Takes a bit of skill and knowhow, but can work well on chaosruns and basically any other place in hell - if this is hardcore though, i would be more wary, it requires more skill and knowhow.
Basically think about what you think is fun... when you're having fun, you play more efficiently and can stay in it for the long haul as well.