I have been repeatedly going between 7 and 10. I don't have the power to get beyond that.
Maybe, if you post your roster, we could try to find a team that is able to beat higher stages.
The fight becomes much easier if you have a champ with "block revive" ability, so the minions of the Ice Golem stay down.
A nice trick is, to use a lot of poison, as this doesn't trigger his reviving hit. The Golem does this attack when his HP-bar drops below a certain level from a hit. If the break-point is reached without a hit, by poison damage, he just doesn't perfom his special attack. I guess this is a kind of bug that wasn't intended when they created the Ice Golem, but I think it will never be reworked.