That's amazing that you were able to beat that instance with only 3 characters. Nice job!

I went back in there last night myself and finally beat him using your suggestion of stacking. I was concerned using the stacking method because my main DPS is a Hunter, so without getting the range he would be useless except for his pet. Everything was going very well until about 20% when he iced my priest and my paladin and my Druid tank was low on health. My druid died and so did everyone else including the warlock pet and hunter pet. My Hunter finished him off with melee, but to be honest I thought it was a wipe at 1% when he keeled over. I guess it was the Warlock dots that finished him. I went on to beat the next boss pretty easily. Ingvar was going very well until about 50% of his second phase. I think I can get him. Thanks for the suggestion.