I'm not sure about the balance of the game, but I'll give my opinion on the card.
The Ice Golem is much weaker at freezing than an octopus. Octuopus freezes for twice as long and doesn't need to be "reborn" every three freezes. Let's say there are two situations, one with four golems, and one with four octopi. The octopi, at 4 creatures each, can easily keep 16 creatures controlled indefinitely.
Four golems:
There are essentially 4 stages of a golem; ice golem with 3 health, 2 health, 1 health, and water golem.
If we have one golem in each stage, they rotate through the stages every four turns, one per turn. Freeze, freeze, freeze, die/reborn. Since one of those freezes is used on a water golem, each golem effectively gets two freezes per four turns. And since freeze lasts two turns, one golem can only control one creature. That's four times less powerful than an octopus.
Ice golems are not immortal. Water golems only have 6 health and can easily be killed.
Water golems cost 4
, while ice golems cost 5. A freeze would cost 1
, meaning it's not any cheaper to play a water golem than an ice golem. Also, 5
for 6 damage is a lot worse than 3
1
for 10 damage.
So I don't really think this card is overpowered at all.